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        검색결과 4,563

        2041.
        2010.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        삼백초 분말의 첨가량을 0-6%로 달리하여 쿠키를 제조한 후 물리화학적 품질 및 관능적 품질특성을 측정하고 각 특성사이의 상관관계를 살펴보았다. 삼백초 분말 첨가량이 증가함에 따라 쿠키의 두께 및 밀도는 유의적으로 증가하였으나(p<0.05), 반죽의 구께 및 밀도에는 영향을 미치지 않는 것으로 나타났다(p>0.05). 반죽과 쿠키의 pH는 삼백초 분말 첨가량이 증가함에 따라 현저하게 감소하였으며, 색 특성 중 명도와 황색도 역시 현저하게 감소한 반면 적색도는 증가하는 경향을 나타내었다. 관능검사 결과, 경도를 제외한 맛, 향미, 색 등의 강도는 분말의 첨가량이 증가함에 따라 유의적으로 증가하여 6% 첨가군이 가장 높게 평가되었다(p<0.05). 한편 상관분석결과 삼백초 분말 첨가 수준은 대부분의 물리화학적 및 관능적 품질특성과 유의적인 상관관계를 나타내어, 삼백초 분말 첨가가 반죽 및 쿠키의 전반적인 품질특성에 상당한 영향을 미치는 것으로 나타났다.
        4,000원
        2042.
        2010.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        감태 분말의 대체량을 0-8%로 달리하여 스펀지 케이크를 제조한 후 물리화학적 및 관능적 품질특성을 측정하고 각 특성사이의 상관관계를 살펴보았다. 감태 분말의 대체비율이 증가함에 따라 반죽의 비중은 점차적으로 증가하는 경향을 나타내었고, 케이크의 비체적은 감태 분말 대체에 따라 감소하고 굽기 손실은 증가하였다. 부피지수는 감소하는 경향을 보여 감태 분말의 비율이 높아지면 케이크의 부피가 작아짐을 알 수 있다. 밝기는 나타내는 L*값은 유의적으로 감소하였으며(p<0.05), 경도는 점차적으로 증가하였다. 관능검사 결과 감태 분말대체에 따라 대부분의 관능 특성이 뚜렷하게 구분되었다(p<0.05). 한편 상관분석 결과 감태 분말의 대체수준은 a*값과 관능적 경도(firmness)를 제외하고 모든 품질특성과 유의적인 상관관계를 나타내었다(p<0.05, p<0.01 또는 p<0.001).
        4,000원
        2043.
        2010.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        기존의 재래식 유탕팽화유과의 문제점을 개선하기 위하여 진공을 이용한 진공팽화기를 설계 제작하였다. 공정변수에 따른 진공팽화유과의 특성을 비교 분석하기 위하여 부피팽화율, 밀도, 절단강도, 색도, 미세구조를 측정하였다. 진공팽화기의 공정변수는 가열온도(100, 120, 140, 160, 180oC), 예열시간(0, 2, 4, 6, 8분), 진공팽화시간(5, 10, 15, 20분)이며, 가열온도 100oC, 예열시간 6분, 진공팽화시간 10분에서 진공팽화유과의 부피팽화율은 10.04로 가장 높게 측정되었고, 밀도는 0.15 g/cm3로 가장 낮게 측정되었지만, 부피팽화율 9.47, 밀도 0.16 g/cm3으로 측정된 가열온도 120oC, 예열시간 4분, 진공팽화시간 5분에서의 진공팽화유과가 유탕유과의 외관 및 조직과 가장 유사하였다. 절단강도는 가열온도 100oC, 예열시간 6분, 진공팽화시간 15분에서 140 g/cm2로 가장 낮게 측정되었다. 색도는 예열시간과 진공팽화시간이 증가함에 따라 백색도가 증가하는 경향을 보였고, 황색도는 감소하는 경향을 보였으며, 적색도는 유의적 차이가 없었다. 진공팽화유과의 백색도(L값)가 유탕팽화유과보다 25정도 높았으며, 적색도(a값)와 황색도(b값)는 유의적 차이는 보이지 않았으며, 진공팽화유과의 미세구조는 가열온도 120oC, 예열시간 4분, 진공팽화시간 5분에서 기공이 작고 균일하였다. 유탕팽화유과와 비교 시 절단강도는 유사하였으나, 부피팽화율은 낮았고, 밀도는 높았다. 셀이 균일하게 형성된 진공팽화의 미세구조와는 달리 유탕팽화유과의 미세구조는 표면과 내부층의 차이가 확인되었다. 진공팽화기의 최적 공정조건은 진공팽화유과의 품질을 고려 할 때, 가열온도 120oC, 예열시간 4분, 진공팽화시간 5분으로 판단되었다.
        4,000원
        2044.
        2010.08 구독 인증기관 무료, 개인회원 유료
        Recently, to improve operating efficiency with the higher in-line rate in automated production lines, a lot of cases of grouping machines and material handling system together to form a cluster has shown frequently. This article addresses the job allocation and operation method of automated material handling for cluster-type production systems. First of all, the control problems of the automated material handling systems are classified into the control problem of inter-cluster material handling system and that of intra-cluster material handling system. Then, a distributed agent-based control scheme is proposed for the former, and an operational control procedure for the latter. Simulation experiment shows that the proposed method is efficient in reducing cycle times and improving utilization of material handling vehicles.
        4,000원
        2045.
        2010.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        인피섬유로 한지를 제조하고 남은 닥나무 목질부를 고부가치화 하기 위하여 닥나무 목질부로 제조된 파티클보드를 이용하여 탄화온도 변화에 따른 닥나무재료 우드세라믹을 제조하여 물성을 검토하였다. 밀 도, 휨강도성능, 브리넬 경도, 압축강도 등은 탄화온도가 증가할수록 증가하였으며 밀도와 휨강도성능, 경도, 압축강도사이에는 유의성이 인정되는 밀접한 상관관계를 나타내었다.
        4,000원
        2046.
        2010.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In order to improve the breaking strength and elongation of Polybutylene succinate (PBS) monofilament, the monofilament was produced by blending PBS and Polybutlyne adipate-co-terephthalate (PBAT). The PBS/PBAT blend monofilament was prepared by the melt spinning system, and the weight ratios of the compositions of PBS/PBAT was 100/0, 95/5, 90/10 and 85/15, respectively. The breaking strength, elongation, softness and crystallization of PBS/PBAT blend monofilament were analyzed by using a tensionmeter, softness measurement, X-ray diffractometer in the both dry and wet conditions. The PBS/PBAT blend monofilaments were spun in the take-up velocity of 1.19m/sec under the drawing ratio of 6.8:1 condition. The production volumes of PBS/PBAT blend monofilaments showed 20% less than that of Nylon. The breaking strength of PBS/PBAT blend monofilaments were decreased as PBAT contents increased, while elongation and softness were increased. In case of PBAT content were over 5%, the breaking strength, elongation and softness of PBS/PBAT blend monofilaments were not shown to increase in spite of increasing in PBAT contents. Based on these results, it was possible to make the monofilaments with the maximized physical properties when the PBAT contents at 5%.
        4,000원
        2047.
        2010.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In the present work, water-based gold nanofluids were synthesized by the solution plasma processing (SPP). The size distribution and the shape of gold nanoparticles in the nanofluids were investigated using high resolution transmission electron microscopy (HR-TEM). The dispersion stability of gold nanofluids was characterized using zeta potential, as well. The thermal properties of gold nanofluids were measured by utilizing lambda measurement device. Nanofluids containing nanoparticles with in diameter were successfully synthesized. As diameter of nanoparticles decreased, dispersion stability of nanofluids increased and the enhanced ratio of thermal conductivity increased. The nanofluid with nanoparticles of in diameter showed approximately 3% improvement in thermal conductivity measurement and this could be due to the enhanced Brownian movement.
        4,000원
        2048.
        2010.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        High speed steels (HSS) were used as cutting tools and wear parts, because of high strength, wear resistance, and hardness together with an appreciable toughness and fatigue resistance. Conventional manufacturing process for production of components with HSS was used by casting. The powder metallurgy techniques were currently developed due to second phase segregation of conventional process. The powder injection molding method (PIM) was received attention owing to shape without additional processes. The experimental specimens were manufactured with T42 HSS powders (59 vol%) and polymer (41 vol%). The metal powders were prealloyed water-atomised T42 HSS. The green parts were solvent debinded in normal n-Hexane at for 24 hours and thermal debinded at mixed gas atmosphere for 14 hours. Specimens were sintered in , gas atmosphere and vacuum condition between 1200 and . In result, polymer degradation temperatures about optimum conditions were found at and . After sintering at gas atmosphere, maximum hardness of 310Hv was observed at . Fine and well dispersed carbide were observed at this condition. But relative density was under 90%. When sintering at gas atmosphere, relative density was observed to 94.5% at . However, the low hardness was obtained due to decarbonization by hydrogen. In case of sintering at the vacuum of torr at temperature of , full density and 550Hv hardness were obtained without precipitation of MC and in grain boundary.
        4,000원
        2049.
        2010.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Multi shell graphite coated Ag nano particles with core/shell structure were successfully synthesized by pulsed wire evaporation (PWE) method. Ar and (10 vol.%) gases were mixed in chamber, which played a role of carrier gas and reaction gas, respectively. Graphite layers on the surface of silver nano particles were coated indiscretely. However, the graphite layers are detached, when the particles are heated up to in the air atmosphere. In contrast, the graphite coated layer was stable under Ar and atmosphere, though the core/shell structured particles were heated up to . The presence of graphite coated layer prevent agglomeration of nanoparticles during heat treatment. The dispersion stability of the carbon coated Ag nanoparticles was higher than those of pure Ag nanoparticles.
        4,000원
        2050.
        2010.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A carbon doped (C-) photocatalyst, which shows good photocatalytic activity to Ultraviolet irradiation and visible irradiation, was successfully prepared by co-grinding of with ethanol or Activated Carbon(C), followed by heat treatment at in air for 60 min. Ethanol and C were used as a representative agent of liquid and solid for carbon doping. Their influence on improving photocatalytic ability and carbon doping degree was studied with degradation of methyl orange and XPS analysis. The product prepared by co-grinding of with Ethanol had Ti-C and C-O chemical bonds and showed higher photocatalytic activity than the product prepared by co-grinding of with C, where just C-O chemical bond existed. As a result, mechanochemical route is useful to prepare a carbon doped photocatalyst activating to visible irradiation, where the solid-liquid operation is more effective than solid-solid operation to obtain a carbon doped .
        4,000원
        2051.
        2010.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Ethylene glycol-based Cu nanofluids were prepared by pulsed wire evaporation (PWE) method. The structural properties of Cu nanoparticles were studied by X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). The average diameter and Brunauer Emmett Teller (BET) surface area of Cu nanoparticles were about 100 nm and , respectively. The thermal conductivity and viscosity of copper nanofluid were measured as functions of Cu concentration and temperature. As the volume fraction of Cu nanoparticles increased, both the enhanced ratios of thermal conductivity and viscosity of Cu nanofluids increased. As the temperature increased, the enhanced ratio of thermal conductivity increased, but that ratio of viscosity decreased.
        4,000원
        2052.
        2010.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Hexagonal barium ferrite () nano-particles have been successfully fabricated by spraypylorysis process. precursor solutions were synthesized by self-assembly method. Diethyleneamine (DEA) surfactant was used to fabricate the micelle structure of Ba-DEA complex under various DEA concentrations. powders were synthesized with addition of Fe ions to Ba-DEA complex and then fabricated powders by spray-pyrolysis process at the temperature range of . The molar ratio of Ba/DEA and heat-treatment temperatures significantly affected the magnetic properties and morphology of powders. powders synthesized with Ba/DEA molar ratio of 1 and heat-treated at showed the coercive forces (iHc) of 4.2 kOe with average crystal size of about 100 nm.
        4,000원
        2053.
        2010.07 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        The usual ceramic process of mixing and milling in state of oxides ZrO2 and CeO2 was adopted in this study in a wet process to manufacture Ce-TZP. CeO2-ZrO2 ceramics containing 8~20 mol% CeO2 were made by heat treatment at 1250~1500˚C for 5hr. The maximum dispersion point of every slurry manufactured with a mixture of ZrO2 and CeO2 was neat at pH10. A stable slurry with average particle size of 90 nm can be manufactured when it is dispersed with the use of ammonia water and polycarboxylic acid ammonium. The sintered Ce-TZP ceramics manufactured with the addition of CeO2 in a concentration of less than 10 mol% progressed to the fracture of the specimen due to the existence of a monoclinic phase of more than 30% at room temperature. More than 99% of the tetragonal phase was created for the sintered body with the addition of CeO2 beyond 18 mol%, but the degradation of the mechanical properties on the entire specimen was brought about due to the CeO2 existing in a percentage above 3%. Consequently, the optimal Ce-TZP level combined in the oxide state was identified to be 16 mol% of CeO2 contents.
        4,000원
        2054.
        2010.07 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        For this paper, we investigated the area specific resistance (ASR) of commercially available ferritic stainless steels with different chemical compositions for use as solid oxide fuel cells (SOFC) interconnect. After 430h of oxidation, the STS446M alloy demonstrated excellent oxidation resistance and low ASR, of approximately 40 mΩcm2, of the thermally grown oxide scale, compared to those of other stainless steels. The reason for the low ASR is that the contact resistance between the Pt paste and the oxide scale is reduced due to the plate-like shape of the Cr2O3(s). However, the acceptable ASR level is considered to be below 100 mΩcm2 after 40,000 h of use. To further improve the electrical conductivity of the thermally grown oxide on stainless steels, the Co layer was deposited on the stainless steel by means of an electroless deposition method; it was then thermally oxidized to obtain the Co3O4 layer, which is a highly conductive layer. With the increase of the Co coating thickness, the ASR value decreased. For Co deposited STS444 with 2 μmhickness, the measured ASR at 800˚ after 300 h oxidation is around 10 mΩcm2, which is lower than that of the STS446M, which alloy has a lower ASR value than that of the non-coated STS. The reason for this improved high temperature conductivity seems to be that the Mn is efficiently diffused into the coating layer, which diffusion formed the highly conductive (Mn,Co)3O4 spinel phases and the thickness of the Cr2O3(S), which is the rate controlling layer of the electrical conductivity in the SOFC environment and is very thin
        4,000원
        2055.
        2010.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        CoSb3 Skutterudites materials have high potential for thermoelectric application at mid-temperature range because of their superior thermoelectric properties via control of charge carrier density and substitution of foreign atoms. Improvement of thermoelectric properties is expected for the ternary solid solution developed by substitution of foreign atoms having different valances into the CoSb3 matrix. In this study, ternary solid solutions with a stoichiometry of Co1-xNixSb3 x = 0.01, 0.05, 0.1, 0.2, CoSb3-yTey, y = 0.1, 0.2, 0.3 were prepared by the Spark Plasma Sintering (SPS) system. Before the SPS synthesis, the ingots were synthesized by vacuum induction melting and followed by annealing. For phase analysis X-ray powder diffraction patterns were checked. All the samples were confirmed as single phase; however, with samples that were more doped than the solubility limit some secondary phases were detected. All the samples doped with Ni and Te atoms showed a negative Seebeck coefficient and their electrical conductivities increased with the doping amount up to the solubility limit. For the samples prepared by SPS the maximum value for dimensionless figure of merit reached 0.26, 0.42 for Co0.9Ni0.1Sb3, CoSb2.8Te0.2 at 690 K, respectively. These results show that the SPS method is effective in this system and Ni/Te dopants are also effective for increasing thermoelectric properties of this system.
        4,000원
        2056.
        2010.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Multilayer Poly methyl methacrylate (PMMA)/ Poly vinyl alcohol (PVA) bone plates were fabricated using electrospinning and in vitro investigations were carried out for pre-clinical biocompatibility studies. The initial cellular cytotoxicity of the methacrylate (PMMA)/ Poly vinyl alcohol (PVA) bone plates was measured by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay using fibroblast-like L-929 cells. Cellular adhesion and differentiation studies were carried out using osteoblast-like MG-63 cells. As simulated body fluid (SBF) contains the same ionic concentration of body fluid and any bioactive material tends to deposit bone-like apatite on the samples surfaces into the SBF, in vitro bioactivity of the multilayer bone plates were investigated using SBF. We also studied the internal organization and tensile strength of the multilayer PMMA/PVA bone plates using micro-computed topography (μ-CT) and universal testing instrument (UTI, Korea) respectively. The cellular cytotoxicity study with MTT confirmed that the cellular viability was 78 to 90% which indicates good cyto-compatibility. Scanning electron microscopic findings revealed a good attachment and adhesion phenomenon of MG-63 cells onto the surfaces of the samples. Cellular differentiation studies also showed that osteogenic differentiation was switched on in a timely manner and affirmed along with that of the control group. Bone-like apatite formation on the surfaces was confirmed within 14 days of SBF incubation. Initial organizations of the multilayer PMMA/PVA bone plates were characterized as dense and uniform. The tensile strength of the post-pressing electronspun mat was higher than that of the pre-electronspun mat. These results suggest that a multilayer PMMA/PVA bone plate system is biocompatible, bioactive and a very good alternative bone plate system.
        4,000원
        2057.
        2010.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Silicon quantum dots (Si QDs) in a superlattice for high efficiency tandem solar cells were fabricated by magnetron rf sputtering and their characteristics were investigated. SiC/Si1-xCx superlattices were deposited by co-sputtering of Si and C targets and annealed at 1000˚C for 20 minutes in a nitrogen atmosphere. The Si QDs in Si-rich layers were verified by transmission electron microscopy (TEM) and X-ray diffraction. The size of the QDs was observed to be 3-6 nm through high resolution TEM. Some crystal Si and -SiC peaks were clearly observed in the grazing incident X-ray diffractogram. Raman spectroscopy in the annealed sample showed a sharp peak at 516 cm-1 which is an indication of Si QDs. Based on the Raman shift the size of the QD was estimated to be 4-6 nm. The volume fraction of Si crystals was calculated to be about 33%. The change of the FT-IR absorption spectrum from a Gaussian shape to a Lorentzian shape also confirmed the phase transition from an amorphous phase before annealing to a crystalline phase after annealing. The optical absorption coefficient also decreased, but the optical band gap increased from 1.5 eV to 2.1 eV after annealing. Therefore, it is expected that the optical energy gap of the QDs can be controlled with growth and annealing conditions.
        4,000원
        2058.
        2010.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Polyvinyl acetate (PVAc) prepared by emulsion polymerization has broad applications for additive such as paint binder, adhesive for wood and paper due to its low glass transition temperature which help to plasticize substrate resins. Since emulsion polymerization has a disadvantage that surfactant and ionic initiator degrade properties of the product polymer, poly (vinyl acetate-eo-ethyl acrylate) (VAc-EA) was synthesized using potassium persulfate as catalyst and polyvinylalcohol (PVA) as protective colloid to prevent the degradation. The copolymer latex product was internally plasticized and has enhanced adhesion, water resistance during VAc-EA emulsion polymerization. No coagulation and complete conversion occur with the reactant mixture of 10 mmol/L potassium persulfate, 10 mmol/L poly ( vinyl alcohol) (PVA 17). As the concentrations of PVA increase, the viscosity becomes increase.
        4,000원
        2059.
        2010.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        EAF dust which is contained around 30% of zinc, 15% of iron and 3% of lead individually, is chemically treated by ammonium chloride, ammonia water, ammonia gas and carbon dioxide, and also tested and identified the ratios of the recovery of In by applied the variations of particle size, pH and heating temperature as well, in order to getting optimized recovery of the In metal after performing all of those processes. Experimental results showed that the rate of Zn recovery is 97% when the mixture of 1.3 of NH4Cl/EAF is heated to the temperature of 400℃ and leached by water, and 95% recovery of In when ammonia gas and carbon dioxide is added simultaneously and adjust the 9.5 of pH to the same mixture above. For the purpose of remove the impurities in the mixed sample, which is prepared by the two samples, indicated above showing as the ratio of 95% and 97% recovery, in case of applied the cementation process to it, and also by electrolytic process, produced the In plate of 95~97%, and acquired 99-99.5% of In metal ingot finally by applied the heating process at 470~500℃.
        4,000원
        2060.
        2010.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Poly(vinyl chloride)-g-poly(styrene sulfonic acid) (PVC-g-PSSA) 가지형 공중합체를 합성한 후, 이를 이용하여 80℃에서 열적으로 환원하여 은 나노입자를 제조하였다. 반응 시간을 바꿈에 따라 다양한 구조의 은 나노입자를 제조하는데 성공하였다. 1시간 정도의 짧은 반응 시간에서는 가지형 공중합체의 미세 상분리 구조를 크게 변화시키지 않고 5 nm 크기의 작은 은 나노입자가 생성되었다. 5시간 정도의 중간 반응 시간에서는 30 내지 50 nm 정도의 크기를 갖는 은 나노입자가 생성되었다. 18시간 정도의 긴 반응 시간에서는, 은입자가 뭉친 허리케인 모양의 은 집합체가 관찰되었다.
        3,000원