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        검색결과 1,435

        242.
        2020.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Metal–organic frameworks (MOFs) are network-like frameworks composed of transition metals and organic ligands containing oxygen or nitrogen. Because of its highly controllable composition and ordered porous structure, it has broad application prospects in the field of material synthesis. In this work, Zn4( PYDC)4(DMF)2∙3DMF (ZPD) was synthesized via a hydrothermal method. Self-doped nitrogen porous carbon ZPDC-T was then prepared by one-step carbonization. The results show that the self-doped nitrogen porous carbon ZPDC-850 has a micro/mesoporous structure with a specific surface area of 1520 m2 g− 1 and a nitrogen content of 6.47%. When a current density is 1.0 A g− 1, its specific capacitance is 265.1 F g− 1. After 5000 times of constant current charging and discharging, the capacitance retention rate was 79.2%. Thus, self-doped nitrogen porous carbon ZPDC-850 exhibits excellent electrochemical properties and good cyclic stability. Therefore, the self-doped nitrogen porous carbon derived from MOFs can be a promising electrode material for supercapacitors.
        4,000원
        243.
        2020.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this work, the correlation between the pore characteristics of activated carbon (AC) and the adsorption/desorption characteristics of evaporated fuel was studied. AC was prepared by various physical re-activation methods using coconut-derived commercial AC. Pore characteristics of the re-activated AC were investigated using N2/ 77 K adsorption isotherms. The structural characteristics of the AC were observed by X-ray diffraction and Raman spectroscopy. The butane working capacity was observed according to ASTM D5228. From the results, the specific surface area and total pore volume of the ACs were determined to be 1380–2040 m2/g and 0.60–0.96 cm3/g, respectively. It was also observed that various pore size distributions were found to be dependent on the functions of the activation method and time. A close relationship between butane activity/ retentivity and micropore/mesopore volumes was found. In addition, it was inferred that the volume fraction of micropores and sub-mesopores with diameters between 1.5 and 3.0 nm primarily controls butane activity.
        4,000원
        244.
        2020.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        This research is conducted to analyze the compatibility of used monomers and produce the high functional hydrogel ophthalmic polymer containing silane and nanoparticles. VTMS (vinyltrimethoxysilane), TAVS [Triacetoxy(vinyl)silane] and cobalt oxide nanoparticles are used as additives for the basic combination of SilM (silicone monomer), MMA (methyl methacrylate) and MA (methyl acrylate). Also, the materials are copolymerized with EGDMA (ethylene glycol dimethacrylate) as cross-linking agent, AIBN (thermal polymerization initiator) as the initiator. It is judged that the lenses of all combinations are optically excellent and thus have good compatibility. Measurement of the optical and physical characteristics of the manufactured hydrophilic ophthalmic polymer are different in each case. Especially for TAVS, the addition of cobalt oxide nanoparticles increases the oxygen permeability. These materials are considered to create synergy, so they can be used in functional hydrogel ophthalmic lenses.
        4,000원
        246.
        2020.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Salacca peel-based porous carbon (SPPC) with high surface area (1945 m2 g−1) and large specific pore volume (1.68 cm3 g−1) was prepared by pre-carbonization and K2CO3 activation method. Based on the TGA results, it can be estimated that up to 70 wt% of sulfur-active materials could be infiltrated into the pores of SPPC to form SPPC/S composite cathode for LiS battery. The porous structure of SPPC could act as a buffer layer against volume expansion and minimize the shuttle effect due to the penetration of intermediate polysulfides during cycle tests. Optimization on sulfur loading (50, 60 and 70 wt%) in SPPCC/S composite was also investigated. It was found that the SPPC/S composites with 60 wt% of sulfur loading had the best electrochemical performances. With 60 wt% of sulfur loading, SPPC/S composite electrodes showed excellent electrochemical performances in terms of high initial specific discharge capacity of 1006 mAh g− 1 at 0.5 C and capacity retention of 71% until the 100th cycle. For both cases of low and high sulfur loading, they caused much worse electrochemical performances. Based on the experimental results, it can be concluded that porous carbons derived from the salacca peel were promising materials for sulfur loading in LiS battery.
        4,000원
        247.
        2020.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A highly functional, environmentally friendly carbonaceous adsorbent material using black liquor (a by-product from the pulp manufacturing) was produced and characterized. This study showed the effect of self-chemical activation driven by inherent alkali, originated from the unique composition of black liquor. A preparation of the micropore-dominant activated carbon was made in an easy and simple manner. The specific surface areas of samples were found to be 718–1591 m2/ g variated upon heat treatment conditions. The sample activated at 850 °C (50 min as retention time) showed the maximum specific surface area of 1591 m2/ g with 13.6% as a production yield. Considering the factors influencing pore structure of activated carbon materials in this study, it was confirmed that mesopore-related surface area increased gradually as the activation temperature and retention time increased. It is noteworthy to address that economically valuable micropore-dominant activated carbon can be produced by a simple heat treatment of the waste material, black liquor. The activated carbon sample derived from black liquor can be applied to various fields, such as environment and energy storage.
        4,000원
        248.
        2020.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, isophorone diisocyanate (IPDI) and dimethylolbutanoic acid (DMBA) were used on the basis of poly caprolactone diol (3M, 3.5M, 4M, 4.5M) for the synthesis of water-based polyurethanes for coating on skin layers of leather. Tensile strength, elongation, and adhesive strength of the prepared samples were measured. As a result of measuring the tensile strength, the tensile strength was found to be 4.09 kgf / mm2 when 3 moles were applied, and 1.071 kgf / mm2 when 4.5 moles were applied. Elongation was 366 % when 3 moles of PCL were applied, and 709 % at 4.5 moles. Adhesive strength was 2.887 kgf / cm when 3 moles of PCL was applied and 0.998 kgf / cm when 4.5 moles were applied.
        4,000원
        249.
        2020.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        For applications in cement-based materials, studies on carbon-based nanomaterials have been almost exclusively on carbon nanotubes, carbon nanofibers, and graphite oxide. Graphene sheets (GPs), as a kind of carbon-based nanomaterials, show unusual mechanical, electrical, optical, and other properties. In this paper, the main focus is to enhance the effect of GPs by improving dispersion through ultrasonication and use of surfactant. Then, dispersion and stability are quantitatively measured by comparing absorbance spectra through spectrophotometry and qualitatively observed through digital imaging and SEM imaging. Therefore, the dispersing protocol is optimized and the most effective and stable dispersion is achieved. At last, the piezoresistivities under compressive load of GPs/cement composites pastes at different additions of GPs are studied by comparing with plain cement paste.
        4,000원
        250.
        2020.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Spinnable mesophase pitch precursor containing more than 98% mesophase content was successfully prepared from FCC-DO (fluid catalytic cracking-decant oil) without hydrogenation or catalytic reaction. The preparation method involved thermal condensation, vacuum treatment, and annealing treatment. Petroleum mesophase pitch-based carbon fibers are produced by melt spinning of pitch precursors, followed by stabilization and carbonization. The resulting carbon fiber exhibited good mechanical performances up to tensile strength of 2.1 GPa and tensile modulus of 212 GPa, with strain-to-failure higher than 1.0%. These properties ensuring that the automotive grade carbon fibers can be successfully prepared from FCC-DO derived petroleum mesophase pitches through the cost-competitive processes.
        4,000원
        251.
        2020.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this paper, we report graphene composite membranes prepared by transfer of a layer of chemical vapor deposition graphene onto porous anodic alumina (AA) substrates with nominal pore size 20 and 30 nm, referred as 20AA and 30AA. The coated and uncoated substrates were characterized using optical and electron microscopy techniques. The bare substrates exhibited a smooth surfaces with a well-organized array of hexagonal pores, displaying an average pore size of 17 ± 3 (20AA) and 23 ± 3 nm (30AA). The scanning electron microscopy and atomic force microscopy analyses confirmed the successful transfer of graphene layer onto the target substrates. The molecular transport study was performed by introducing 0.5 M potassium chloride (KCl) and deionized water in a Side-bi-Side Franz diffusion cell. The graphene/20AA specimen blocked 66% ions transport, and graphene/30AA membrane about 64%. The ions blockage exceeded 90%, near the characteristics of defectfree graphene when the defects of the transferred graphene were sealed with Nylon 6,6. The results of this study suggest the potential use of graphene on AA substrates for water desalination and gas purification applications.
        4,200원
        253.
        2019.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        The purpose of this study is to fabricate an ophthalmic lens by copolymerizing two types of carbon nanotubes and hydrophilic hydrogel lens materials, and to investigate its application as an ophthalmic lens material by analyzing its physical properties and antimicrobial effect. For polymerization, HEMA (2-hydroxyethyl methacrylate), EGDMA (ethylene glycol dimethacrylate), a crosslinking agent, and AIBN (azobisisobutyronitrile), an initiator, are used as a basic combination, and a single-walled carbon nanotube and a single-walled, carboxylic-acid-functionalized carbon nanotube are used as additives. To analyze the physical properties, the water content, refractive index, breaking strength, and antimicrobial effect of the fabricated lenses are measured. The fabricated lenses satisfies all the basic properties of the basic hydrogel ophthalmic lens. The water content increases with increasing amount of additive and decreases with addition of 0.2% ratio of nanoparticles. The refractive index is inversely proportional to the water content result. As a result of the antimicrobial test of the fabricated lens, the addition of carbon nanotubes shows an excellent antimicrobial effect. Therefore, it is considered that the fabricated lens can be applied as a functional material for basic ophthalmic hydrogel lenses.
        4,000원
        254.
        2019.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Nanoporous carbon/MnO2 (C–MnO2) composites with foam-like structure based on modified nitrile butadiene rubber were achieved by thermal treatment, followed by alkaline solution etching and dipping method. The XRD, nitrogen adsorption and desorption, and SEM and TEM were used to characterize the microstructure of the obtained C–SiO2, C and C–MnO2. Finally, all the obtained samples have been used in three-electrode system to study the electrochemical properties including cyclic voltammetry, galvanostatic charge/discharge and AC impedance for supercapacitor. The study found that the specific capacity of C–MnO2 electrode material for supercapacitor could reach as high as 109 F/g under the current density of 0.5 A/g, which is much higher than those of the other two. These superior electrochemical properties are attributed to the synergistic effect MnO2 particles with the C matrix which functions as a conductive support.
        4,000원
        255.
        2019.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구의 목적은 질산, 황산, 암모니아수, 과산화수소에 대한 생태독성평가를 통해서 사고대비물질들에 대한 기초 독성 데이터베이스를 구축하여, 향후 화학사고 발생시 환경 피해에 관한 의사결정에 과학적 근거를 제공하는 데 있다. 이를 위해 본 연구에서는 사고대비물질 중 토양의 물리·화학적 성질을 변화시킬 수 있는 질산, 황산, 암모니아수, 과산화수소를 대상으로 국내 토착 절지동물인 김어리 톡토기 (Paronychiurus kimi)를 이용한 생태독성평가를 수행하였다. 7일간의 급성독성평가와 28일간의 만성독성평가를 수행하였으며, 시험물질 농도에 따른 토양의 pH 변화를 관찰하였다. 토양의 pH는 질산, 황산, 과산화수소, 암모니아수의 농도가 10,000 mg kg-1 soil dry wt.일 때, 각각 2.86, 2.72, 7.18, 9.69이었다. 질산, 황산, 과산화수소, 암모니아수에 대한 만성독성평가 결과, LC50 값은 각각 2,703, 5,414, 3,158, 859 mg kg-1 soil dry wt.이었으며, P. kimi의 산란 수에 대한 EC50 값은 각각 587, 2,148, 1,300, 216 mg kg-1 soil dry wt.이었다. 비록 본 연구에서는 사고대비물질들의 유입에 따른 토양 pH의 변화만이 조사되었지만, 본 연구의 결과는 P. kimi가 사고대비물질에 의해 변화된 토양의 pH뿐만 아니라 사고대비물질의 유입에 의해 감소된 유기물 함량과 생성된 반응 산물에 의해서도 사망률과 산란수에 영향을 받을 수 있음을 의미한다. 대부분의 사고대비물질들이 토양의 특성을 변화시킬 수 있다는 점을 감안할 때, 토양의 특성 변화와 이에 따른 생물 영향을 고려한 화학사고 후 평가 및 복원 방법이 필요하다.
        4,000원
        256.
        2019.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The purpose of this study was to investigate the quality of dehulled soybean (DHSB), and the rapid preparation possibility of soybean milk with DHSB (SM-DHSB), and then the quality of SM-DHSB. In DHSB, the moisture content decreased, the crude protein, crude fat, minerals, and carbohydrate contents increased, and the isoflavone (daidzein, genistein and glycitein) content was similar to that of soybean (SB). The water absorption rate of DHSB for soybean milk preparation was higher than that of SB. In the results of SM-DHSB and soybean milk (SM) qualities, the crude protein content, total solid content, and the viscosity of SM-DHSB were higher, the yield and the proximate composition (except crude protein) were similar, and the Biji production rate, and total dietary fiber content of SM-DHSB were lower compared to the SM. In terms of the isoflavone contents of SM-DHSB, daidzein and genistein content were similar, and glycitein content was lower compared with the SM. Consequently, these results suggest the possible use of DHSB for rapid SM-DHSB preparation, because the soaking time was decreased by the high water absorption rate of DHSB in the SM preparation, and the quality of SM-DHSB improved compared to those of the SM.
        4,000원
        257.
        2019.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Titanium dioxide (TiO2) is a typical inorganic material that has an excellent photocatalytic property and a high refractive index. It is used in water/air purifiers, solar cells, white pigments, refractory materials, semiconductors, etc.; its demand is continuously increasing. In this study, anatase and rutile phase titanium dioxide is prepared using hydroxyl and carboxyl; the titanium complex and its mechanism are investigated. As a result of analyzing the phase transition characteristics by a heat treatment temperature using a titanium complex having a hydroxyl group and a carboxyl group, it is confirmed that the material properties were different from each other and that the anatase and rutile phase contents can be controlled. The titanium complexes prepared in this study show different characteristics from the titania-formation temperatures of the known anatase and rutile phases. It is inferred that this is due to the change of electrostatic adsorption behavior due to the complexing function of the oxygen sharing point, which crystals of the TiO6 structure share.
        4,000원
        258.
        2019.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        버섯 균사체 배양물을 이용한 식초개발 결과는 다음과 같다. 버섯 균사체 배양물의 베타글루칸 함량 분석결과 현미에서는 29.2 mg/g이었으나 버섯 균사체 배양물에서 함량이 증가하여 상황 78.7 mg/g, 동충하초 46.6 mg/g, 노랑느타리 19.9 mg/g 순으로 나타났다. 또한 동충하초 배양물은 조지방과 베타글루칸 함량이 상대적으로 높고, 코디세핀도 0.34 mg/g 함유되어 있었다. 버섯 균사체 배양물 첨가에 따른 알코올 발효특성은 건조시료 중에서는 현미, 동충하초가 생시료 중에서는 노랑느타리의 알코올 생성능이 높았으며, 초산발효 시 산도는 건조시료에서는 노랑느타리가, 생시료에서는 현미의 산도가 높았다. 버섯 균사체 배양식초의 이화학적 특성 분석결과 건조시료 중 노랑느타리와 동충하초 식초가 산도가 높고 환원당 함량이 높은 것으로 나타났으며 기호도 평가 결과 노랑느타리와 동충하초 균사체 식초가 현미식초에 비해 기호도가 높았고 이취는 낮은 것으로 나타났다. 버섯 균사체 식초의 기능성분 분석결과 동충하초 식초는 폴리페놀이 우수하였고 또한, 코디세핀이 786 mg/L 함유되어 있으며, 노랑느타리 식초는 베타글루칸 함량이 20.9 mg/g으로 높은 것으로 나타났다. 본 연구에서 버섯 균사체를 활용한 발효식초 제조에 적합한 균으로는 동충하초와 노랑느타리가 적합한 것으로 나타났으며, 향후 적정 초산 발효기간, 보존 방법 등의 추가 연구가 필요할 것으로 판단된다.
        4,000원
        259.
        2019.12 KCI 등재후보 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 우수한 미백 및 주름 개선 기능을 갖는 천연 유래 해초추출물 톱니모자반 추출물(학명 Sargassum serratifolium, MES)의 저장 안정성과 피부투과성을 향상시키는 목적으로 oil-in-water (O/W) 나노 에멀젼 구조를 적용하였으며 나노에멀젼에 대한 최적의 제조 조건을 연구하였다. 톱니모자반으로부터 추출되어 농축, 탈염 및 탈당 과정을 거친 MES의 주성분은 소수성의 활성성분으로 구성되어 있어 산화가 쉽게 일어나고 화장품 성분으로 사용하기에는 적합하지 않다. 본 연구에서는 PEG 400, 폴리옥실 캐스터오일 (EL), Poloxamer 407 등 다양한 계면활성 제와 첨가제 성분을 사용하여 MES가 함유된 O/W 나노에멀젼을 제조하였다. 그 과정에서 사용된 구성성분의 배합순 서와 화학적 조성 비율이 미치는 영향을 체계적으로 연구하였다. 최적화된 조건에서 제조된 나노에멀젼의 평균 크기는 20 ~ 30 nm 범위로 나타났으며, 시간 변화에 따른 나노에멀젼의 멜라닌 합성 억제 효율 성능은 5 사이클의 시간 변화에도 큰 차이가 없었다. 이것은 나노에멀젼의 우수한 장기간 저장 안정성과 피부투과성을 시사한다.
        4,000원
        260.
        2019.11 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        In this paper, a water-based green polymer mud is synthesized by simple compounding method. Effects of different kinds of tackifiers, their molecular weight on the viscosity of polymer mud and the effects of different fluid loss additives on mud fluid loss are studied. The results show that when polystyrene and anionic polyacrylamide with molecular weight of 8 ~ 10 million are used as the main thickening ingredient, polymer mud with high viscosity and high stability can be obtained. When the prepared polymer mud is formulated as NPAM: PEO: Hydroxypropyl cellulose(HPC) :Water = 42:10:10:100000 (unit: kg), the viscosity can reach 20.6 s, the filtration loss in 7.5 min is 24 mL, and the sand content is only 0.1%. Compared with traditional bentonite mud, the green environment-friendly polymer mud has the advantages of small amount of waste, low environmental pollution, and low pulping cost, and can meet the construction needs for most topography and geomorphology drilling engineering
        4,000원