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        검색결과 4,666

        2001.
        2011.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        원자전달 라디칼 중합(ATRP)에 의해 poly(vinyl chloride) (PVC) 주사슬과 poly(styrene sulfonic acid) (PSSA) 곁사슬로 되어있는 양쪽성 PVC-g-PSSA 가지형 공중합체를 합성하였다. 합성된 고분자 전해질막을 10 wt% AgNO3 수용액에 담가 은이온으로 이온교환을 하였으며, 환원제를 통하여 은 나노입자를 성장시켰다. UV분광학과 XRD 분석을 통해 은 나노입자 성장을 확인하였다. 투과전자현미경(TEM) 분석결과 NaBH4를 사용하였을 때 10~20 nm 크기의 은 나노입자를 얻는데 가장 효과적임을 알 수 있었다. 또한 은 나노입자의 성장은 환원제의 농도와 환원 시간에 크게 영향을 받았다.
        4,000원
        2002.
        2011.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The optimal replaced percentage of brown rice Jeung-pyun was investigated in this study. A specific volume of brown rice Jeung-pyun resulted in no difference. The pH of Jeung-pyun (5.10-5.39) was higher than that of Jeung-pyun dough (4.96-5.17). The lightness darkened to 55.39-63.56, as the replaced amount of brown rice flour was increased. Furthermore, redness and yellowness increased to 3.24-4.15 and 4.45-10.12, respectively. The microstructure examined by scanning electron microscopy became enlarged and irregular as the amount of replaced rice increased. The gelatinization of 30-40% brown rice powder was approximately 1.93-2.20. The mechanical textures of hardness, gumminess, chewiness, and fracturability were high as additional ingredients and the storage period increased, whereas adhesiveness, springiness, and cohesiveness were low. The results of a sensory evaluation revealed that the 30% added brown rice Jeung-pyun was highly assessed as the most appropriate percentage of added brown rice Jeung-pyun.
        4,000원
        2003.
        2011.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Recently, nanotubes have considerably researched because of their novel application about photocatalysis, dye-sensitized solar cells (DSSCs), lithium ion battery, etc. In this work, self-standing nanotube arrays were fabricated by anodic oxidation method using pure Ti foil as a working electrode in ethylene glycole with 0.3M + . Growth behavior of nanotube arrays was compared according to temperature, voltage and time. The morphology, structure and crystalline of anodized nanotube arrays were observed by FE-SEM (field emission scanning electron microscope) and XRD (X-ray diffraction).
        4,000원
        2004.
        2011.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Ni nanowires were fabricated using anodic aluminum oxide (AAO) membrane as a template by electrochemical deposition. The nanowires were formed within the walls of AAO template with 200 nm in pore diameter. After researching proper voltage and temperature for electrochemical deposition, the length of Ni nanowires was controlled by deposition time and the supply of electrolyte. The morphology and microstructure of Ni nanowires were investigated by field emission scanning electron microscope (FE-SE), X-ray diffraction (XRD) and transmission electron microscope (TEM).
        4,000원
        2005.
        2011.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        As a pore precursor, carbon black with different content of 0 to 60 vol% were added to (Ba,Sr) powder. Porous (Ba,Sr) ceramics were prepared by pressureless sintering at for 1h under air. Effects of carbon black content on the microstructure and PTCR characteristics of porous (Ba,Sr) ceramics were investigated. The porosity of porous (Ba,Sr) ceramics increased from 6.97% to 18.22% and the grain size slightly decreased from to with increasing carbon black contents. PTCR jump of the (Ba,Sr) ceramics prepared by adding carbon black was more than , and slightly increased with increasing carbon black. The PTCR jump in the (Ba,Sr) ceramics prepared by adding 40 vol% carbon black showed an excellent value of , which was above two times higher than that in (Ba,Sr) ceramics. These results correspond with Heywang model for the explanation of PTCR effect in (Ba,Sr) ceramics. It was considered that carbon black is an effective additive for preparing porous based ceramics. It is believed that newly prepared (Ba,Sr) cermics can be used for PTC thermistor.
        4,000원
        2006.
        2011.01 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        To improve the chemical stability of metal, the ceramic coatings on metallic materials have attracted interest from many researchers due to the chemical inertness of ceramic materials. To endure strong acids, SiOC coating on metal substrate was carried out by dip coating method using 20wt% polyphenylcarbosilane solution; SiC powder was added to the solution at 10wt% and 15wt% to improve the mechanical properties and to prevent cracks of the film. Thermal oxidation as a curing step was carried out at 200˚C for crosslinking of the polyphenylcarbosilane, and the coating samples were pyrolysized at 800˚C under argon to convert the polyphenylcarbosilane to SiOC film. The thicknesses of the SiOC coating films were 2.36μm and 3.16μm. The quantities of each element were measured as SiO1.07C6.33 by EPMA, and it can be confirmed that the SiOC film from polyphenylcarbosilane was formed in a manner that was carbon rich. The hardness of the SiOC film was found to be 3.2Gpa through nanoindentor measurement. No defect including cracks appeared in the SiOC film. The weight loss of the SiOC coated stainless steel was within 2% after soaking in 10% HCl solution at 80˚C for one week. From these results, SiOC coating shows good potential for application to protect against severe chemical corrosion of stainless steel.
        4,000원
        2008.
        2010.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Magnesium hydroxide-melamine core-shell particles were prepared through the coating of melamine monomer on the surface of magnesium hydroxide in the presence of phosphoric acid. The melamine monomer was dissolved in hot water but recrystallized on the surface of magnesium hydroxide by quenching to room temperature in the presence of phosphoric acid. The core-shell particle was applied to low-density polyethylene/ ethylene vinyl acetate (LDPE/EVA) resin by melt-compounding at 180˚C as flame retardant. The effect of magnesium hydroxide and melamine content has been studied on the flame retardancy of the core-shell particles in LDPE/EVA resin according to the preparation process and purity of magnesium hydroxide. Magnesium hydroxide prepared with sodium hydroxide rather than with ammonia solution revealed higher flame retardancy in core-shell particles with LDPE/EVA resin. At 50 wt% loading of flame retardant, core-shell particles revealed higher flame retardancy compared to that of the exclusive magnesium hydroxide in LDPE/EVA composite, and it was possible to satisfy the V0 grade in the UL-94 vertical test. The synergistic flame retardant effect of magnesium hydroxide and melamine core-shell particles was explained as being due to the endothermic decomposition of magnesium hydroxide and melamine, which was followed by the evolution of water from the magnesium hydroxide and porous char formation due to reactive nitrogen compounds, and carbon dioxide generated from melamine.
        4,000원
        2009.
        2010.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        TiO2 nanowires were self-catalytically synthesized on bare Si(100) substrates using metallorganic chemical vapor deposition. The nanowire formation was critically affected by growth temperature. The TiO2 nanowires were grown at a high density on Si(100) at 510˚C, which is near the complete decomposition temperature (527˚C) of the Ti precursor (Ti(O-iPr)2(dpm)2). At 470˚C, only very thin (< 0.1μm) TiO2 film was formed because the Ti precursor was not completely decomposed. When growth temperature was increased to 550˚C and 670˚C, the nanowire formation was also significantly suppressed. A vaporsolid (V-S) growth mechanism excluding a liquid phase appeared to control the nanowire formation. The TiO2 nanowire growth seemed to be activated by carbon, which was supplied by decomposition of the Ti precursor. The TiO2 nanowire density was increased with increased growth pressure in the range of 1.2 to 10 torr. In addition, the nanowire formation was enhanced by using Au and Pt catalysts, which seem to act as catalysts for oxidation. The nanowires consisted of well-aligned ~20-30 nm size rutile and anatase nanocrystallines. This MOCVD synthesis technique is unique and efficient to self-catalytically grow TiO2 nanowires, which hold significant promise for various photocatalysis and solar cell applications.
        4,000원
        2010.
        2010.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Most TCOs such as ITO, AZO(Al-doped ZnO), FTO(F-doped SnO2) etc., which have been widely used in LCD,touch panel, solar cell, and organic LEDs etc. as transparent electrode material reveal n-type conductivity. But in order to realizetransparent circuit, transparent p-n junction, and introduction of transparent p-type materials are prerequisite. Additionalprerequisite condition is optical transparency in visible spectral region. Oxide based materials usually have a wide optical band-gap more than ~3.0eV. In this study, single-phase transparent semiconductor of SrCu2O2, which shows p-type conductivity, havebeen synthesized by 2-step solid state reaction at 950oC under N2 atmosphere, and single-phase SrCu2O2 thin films of p-typeTCOs have been deposited by RF magnetron sputtering on alkali-free glass substrate from single-phase target at 500oC, 1%H2/(Ar+H2) atmosphere. 3% H2/(Ar+H2) resulted in formation of second phases. Hall measurements confirmed the p-typenature of the fabricated SrCu2O2 thin films. The electrical conductivity, mobility of carrier and carrier density 5.27×10−2S/cm,2.2cm2/Vs, 1.53×1017/cm3 a room temperature, respectively. Transmittance and optical band-gap of the SrCu2O2 thin filmsrevealed 62% at 550nm and 3.28eV. The electrical and optical properties of the obtained SrCu2O2 thin films deposited by RFmagnetron sputtering were compared with those deposited by PLD and e-beam.
        4,000원
        2011.
        2010.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        In this paper, double texturization of multi crystalline silicon solar cells was studied with laser and reactive ion etching (RIE). In the case of multi crystalline silicon wafers, chemical etching has problems in producing a uniform surface texture. Thus various etching methods such as laser and dry texturization have been studied for multi crystalline silicon wafers. In this study, laser texturization with an Nd:YVO4 green laser was performed first to get the proper hole spacing and 300μm was found to be the most proper value. Laser texturization on crystalline silicon wafers was followed by damage removal in acid solution and RIE to achieve double texturization. This study showed that double texturization on multi crystalline silicon wafers with laser firing and RIE resulted in lower reflectance, higher quantum yield and better efficiency than that process without RIE. However, RIE formed sharp structures on the silicon wafer surfaces, which resulted in 0.8% decrease of fill factor at solar cell characterization. While chemical etching makes it difficult to obtain a uniform surface texture for multi crystalline silicon solar cells, the process of double texturization with laser and RIE yields a uniform surface structure, diminished reflectance, and improved efficiency. This finding lays the foundation for the study of low-cost, high efficiency multi crystalline silicon solar cells.
        4,000원
        2012.
        2010.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        목 적: 본 연구는 고함수 하이드로젤 렌즈를 제조하기 위해 일반적으로 사용되는 콘택트렌즈의 재료와 MPTS(methacryloxypropyl tris(trimethylsiloxy)silane) 및 DMA(N,N-dimethylacrylamide)를 각각 첨가하여 중합한 후 이 재료들의 첨가 비율을 증가시켜 물리적 특성을 평가하였다. 방 법: MPTS와 DMA를 교차결합제인 EGDMA와 HEMA, NVP, MMA 그리고 개시제인 AIBN을 사용하여 캐스트 몰드법으로 공중합 하였다. 결 과: 실험결과, DMA를 첨가하여 제조한 콘택트렌즈의 함수율은 43.32~64.65%, 산소전달률(Dk)은 13.55~33.55×10(-11)(cm2/sec)(mlO2/ml×mmHg)이었다. MPTS를 첨가하여 제조한 콘택트렌즈의 경우, 함수 율은 41.02~47.62%, 산소전달률(Dk)은 13.88~20.38×10-11(cm2/sec)(mlO2/ml×mmHg)이었다. DMA가 첨가된 조합에서는 함수율이 증할수록 산소전달률(Dk)이 증가하는 경향을 보였지만 MPTS가 첨가된 조합에서는 함수율이 증가하여도 산소전달률(Dk)은 일정하게 유지되는 경향을 보였다. 결 론: 본 실험결과로 볼 때 생성된 공중합체는 고함수율을 가진 안의료용 재료로 사용될 수 있을 것으로 판단된다.
        4,000원
        2013.
        2010.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 국내 제조업의 기술혁신 패턴을 산업의 기술집약도에 따라 4개 부문-고기술, 중상기술, 중하기술 및 저기술-으로 나누어 살펴보았다. 과학기술정책연구원의 기술혁신조사(KIS 2008) 데이터를 이용한 실증분석 결과, 국내 기술혁신 패턴은 산업의 기술 수준이 높고 낮음에 관계없이 모든 산업부문에서 Pavitt의 과학기반형 특성을 나타내는 것으로 확인되었다. 이러한 결과는 고기술산업과 저기술산업의 기술혁신 패턴이 각각 Pavitt의 과학기반형(science-based)과 공급자주도형(supplier-dominated)으로 뚜렷하게 구분되는 해외 연구결과와는 차이를 나타낸다. 이는 국내 기술혁신활동이 해당 산업의 기술수준이나 특성을 제대로 반영하지 못한 채 고기술산업을 기준으로 획일화되어 있음을 보여주는 것이다. 향후 각 산업의 기술수준이나 특성을 반영하는 효과적인 기술·혁신정책 수립을 위해서는 국내 기술혁신 패턴이 이러한 양상을 나타내는 원인과 그것이 혁신성과에 미치는 영향에 대한 추가적인 연구가 필요하다 하겠다.
        6,400원
        2014.
        2010.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Camellia sinensis L. (green tea) seed oils were prepared by roasting at 213℃ and pressing (RP), pressing (P), and nhexane extraction (H). The physico-chemical properties of the RP, P, and H samples, including fatty acid composition, color, and sensory characteristics were analyzed. RP, P and H samples were thermally oxidized at 180℃, and oxidative stability was determined by DPPH, CDA, and p-AV at 0, 20, 40, 60, and 80 min. Compared to the P and H samples, RP resulted in significantly higher thermal oxidative stability according to the DPPH, CDA, and p-AV results (p〈0.05). The ratio of unsaturated fatty acids to saturated fatty acids among RP, P, and H samples were significantly different (p〈0.05). The oleic acid and linoleic acid contents in green tea seed oils were 58 and 23%, respectively. Hunter's color value of lightness (L) for the RP, P, and H samples was not significant. Redness (a) of RP was 3.47±0.119 and yellowness (b) of H was 60.10±2.483, which were significantly different. Compared to RP samples, H and P samples had the highest color and off-odor values in the sensory evaluation. RP samples showed the highest taste value and were significant overall (p〈0.05). The thermal stability of RP extraction was more stable than any other method. Camellia sinensis L. seed oil extracted by RP had better sensory characteristics than other edible oils, including soybean oil, grape seed oil, and extra virgin olive oil.
        4,000원
        2015.
        2010.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The principal objective of this study was to determine the optimal mixing conditions for three amounts of onion powder, sugar, and butter to prepare onion powder cookies. The experimental design was based on the central composite design methodology of response surface, which included 16 experimental points including two replicates for onion powder, sugar, and butter. The mechanical and sensory properties of the cookies were measured, and these values were applied to the mathematical models. A canonical form and perturbation plot showed the influence of each ingredient on the mixed final product. The results of the spread ratio did not show significant results, but hardness increased with increasing quantities of onion powder and sugar but decreased with butter (p<0.01). The color lightness "L" value increased with increasing quantities of sugar and butter but decreased with added onion powder. In contrast, the redness color "a" value increased with increasing quantities of onion powder and sugar. Sugar did not affect the yellowness color "b" value, but the color b value increased with increasing onion powder and sugar. The results of a sensory evaluation using the predicted model showed significant values for flavor (p<0.01), texture (p<0.05), taste (p<0.05), and overall quality (p<0.01). As a result, the optimum formulation by numerical and graphical methods was calculated as 12.58 g onion powder, 35 g sugar, and 52.38 g butter.
        4,000원
        2016.
        2010.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Bamboo leaf powder was added to Jeolpyun to increase the neutraceutical effects and storage period. The bamboo leaf powder was added to rice flour at ratios of 0, 4, 6, 8, and 10% (w/w), and they were treated with aqueous malt extract to extend storage. The Jeolpyun was stored at 20℃ for 72 hr, and the physical and sensory characteristics were evaluated. As a result, the crude fat, crude protein, moisture, crude ash and total dietary fiber contents in bamboo leaf powder were 4.36, 11.29, 3.37, 7.33, and 65.57%, respectively. The Hunters L, a, and b values decreased significantly as the amount of bamboo leaf powder increased; however, the a and b values increased during storage. The paste property setback values decreased with the malt extract treatment and with increasing amounts of bamboo leaf powder. In a sensory analysis, hard texture strength in the malt extract and bamboo leaf powder treatment groups was less than that in the control during storage. The Jeolpyun prepared with malt extract and no bamboo leaf powder was the most accepted by consumers. Although adding bamboo leaf powder resulted in less consumer acceptance except for the flavor attribute, adding 4% and 8% bamboo leaf powder resulted in better consumer acceptance for texture, taste, and overall acceptance than that of the control. In a microbial analysis, adding bamboo leaf powder resulted in fewer mold colonies. In conclusion, adding 4% bamboo leaf powder and malt extract to Jeolpyun improved its storage properties.
        4,000원
        2017.
        2010.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Research was conducted on vinegar types and characteristics with reference to representative literature such as SanGaYoRok, SikRyoChanYo, SooEunJabBang, GoSaChalYo, DongEuiBoGam, SaSiChanYoCho, JuBangMoon, ShinGanGuWhang, ChalYoSeo, EumSikDiMiBang, YoRok, ChiSengYoRam, SanRimKyoungJae,EumSikBo,OnJuBeop, SulManDeuNunBeop, KyuHapChongSeo, ImWonSipYukJi, JungIlDangJabJi, SulBitNeunBeop, SiUiJeonSeo, and BuInPilJi from the 15th to the 19th centuries of the Joseon Dynasty. Based on this research, a classification of materials used in vinegar, knowledge on treatment, preparation of ingredients, capturing flavor, storage of vinegar, as well as the favorable days that vinegar can be manufactured were studied and analyzed based on the different aspect of vinegar. Vinegar is a wellknown condiment throughout the world and has the potential of becoming a luxurious food. Replication and further analysis to expand the properties of vinegar is necessary using old literature, together with the literature identified above. Based on ongoing research, it is foreseeable that the development of a vinegar with unique characteristics and improved standards will be the foundation for the globalization of Korean cuisine, which is our current focus.
        6,700원
        2018.
        2010.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The objective of this study was to develop functional rice coated with yacon roots extracts and to evaluate the antioxidant properties and physiological activity of rice coated with yacon extract. The washed rice was coated by spraying yacon extract at 10, 20, 30, and 40 °Brix and dried at room temperature. The moisture contents, color changes, antioxidant properties as total polyphenolics and DPPH radical scavenging activity and instrumental texture property and sensory evaluation change in the yacon root extracts coated rice and uncoated cooked rice were observed during 3 days of storage. Increasing the coating concentration was associated with lower color values(L value) and moisture contents. Total phenolics and DPPH radical scavenging properties generally increased in the cooked rice coated with yacon root extract more than the control (non-coated rice). However, D-20(20 °Brix of the yacon root concentration) resulted in better textural properties and sensory overall acceptability in cooked rice on 0 and 3 storage days. It was concluded that the optimum coating ration of rice and added functional yacon rice were 20 °Brix and 7% respectively, in proportion to the total weight of raw rice.
        4,000원
        2019.
        2010.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We developed functional synthetic lubricant for internal combustion engine oil, which would improve engine oil performance for internal combustion engine and extend engine life. We made base oil by synthesizing nonanoic acid, 1.1.1-trimethylol propane (which has good bio-degradability) and pentaerythrytol ester. We synthesized catalyst using p-toluene sulfonic acid 0.15 wt% and coloring-prevention agent hypo-phosphorus acid 0.18 wt% at 180-190℃. Reaction temperature was increased at the rate of 10℃ for every 1 hour. When acid value reached below 3, reaction was completed. After cooling and deoxidization, we washed it by distilled water two times. After dehydration and filtering, we obtained trimethylol propane tripelargonate (TMTP) and pentaerythrytol tetrapelargonate (PETP) at yields of 96 % and 98 % respectively.
        4,000원
        2020.
        2010.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Regenerated cellulose fibers were prepared from three pulps containing different degree of polymerization(DP) and α-cellulose contents by dry-jet wet spinning technique with cellulose dope in N-methylmorpholin N-oxide (NMMO). The effect of antioxidant, n-propyl gallate (PG) on the properties of different regenerated celluloses was studied using X-ray diffraction, copper number calculation, and viscometry. The degradaqtion of regenerated cellulose from pulp containing higher DP and lower α-cellulose content was occurred more seriously. The tensile strength and initial modulus of regenerated cellulose fiber obtained from NMMO dope with PG were higher than those of fiber obtained from NMMO dope without PG. All fibers showed the round shape cross section and typical cellulose II crystalline structure.
        4,000원