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        검색결과 1,527

        41.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Hierarchically porous carbon foam composites with highly dispersed Fe2O3 nanoparticles confined in the foam pores, facilely fabricated by hydrolysis-driven emulsion polymerization strategy. The as-generated acidic conditions of Fe3+ hydrolysis could catalyze the polymerization of phenolic resin, and the carbon-based composite materials containing iron oxides were obtained in situ. The structural characterization results show that HCF@Fe2O3 NPs-2 electrode has the largest specific surface area (549 m2/ g) and pore volume (0.46 cm3/ g). Electrochemical results indicates that typical HCF@Fe2O3 NPs-2 electrode displays good capacitive properties. including high specific capacitance (225 F/g at 0.2 A/g current density). Excellent magnification performance (capacity retention rate 80% as current density increases from 0.2 to 10 A/g). At the same time, HCF@SnO2 NPs was successfully synthesized by replacing hydrolyzed tin tetrachloride with ferric chloride. This study provides a new idea for the preparation of metal oxide–carbon matrix composites, and also highlights the potential of such carbon foams in application of energy storage.
        4,000원
        42.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Pharmaceutical products occurring in freshwater bodies create numerous problems for the water bodies owing to their bio-toxic nature. In order to remove such pharmaceutical pollutants, a novel Er-doped Bi4O5Br2/ g-C3N5 nanocomposite was prepared by one-pot synthesis and applied for the photocatalytic removal process. The Er ions doped on the surface of Bi4O5Br2/ g-C3N5 nanocomposite exhibited 97% degradation of tetracycline in 60 min under visible light irradiation, which is higher than pure g-C3N5 and Bi4O5Br2 photocatalysts. The improved photocatalytic properties are attributed to the outstanding visible light harvesting capacity and quick charge carrier separation efficiency which greatly reduced the recombination rate in the heterojunctions. Based on radical trapping experiments, the •O2 −, h+ and •OH radicals played a prominent role in the photodegradation reactions under visible light. Finally, the ternary Er-doped Bi4O5Br2/ g-C3N5 nanocomposite is effectively recyclable with quite a stable photocatalytic removal rate. This work enables a new perspective on the rational design of rare-earth-based nanocomposites for various pharmaceutical pollutants treatment processes.
        4,000원
        43.
        2023.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        β-Ga2O3 has become the focus of considerable attention as an ultra-wide bandgap semiconductor following the successful development of bulk single crystals using the melt growth method. Accordingly, homoepitaxy studies, where the interface between the substrate and the epilayer is not problematic, have become mainstream and many results have been published. However, because the cost of homo-substrates is high, research is still mainly at the laboratory level and has not yet been scaled up to commercialization. To overcome this problem, many researchers are trying to grow high quality Ga2O3 epilayers on hetero-substrates. We used diluted SiH4 gas to control the doping concentration during the heteroepitaxial growth of β-Ga2O3 on c-plane sapphire using metal organic chemical vapor deposition (MOCVD). Despite the high level of defect density inside the grown β-Ga2O3 epilayer due to the aggregation of random rotated domains, the carrier concentration could be controlled from 1 × 1019 to 1 × 1016 cm-3 by diluting the SiH4 gas concentration. This study indicates that β-Ga2O3 hetero-epitaxy has similar potential to homo-epitaxy and is expected to accelerate the commercialization of β-Ga2O3 applications with the advantage of low substrate cost.
        4,000원
        44.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Highly safe lithium-ion batteries (LIBs) are required for large-scale applications such as electrical vehicles and energy storage systems. A highly stable cathode is essential for the development of safe LIBs. LiFePO4 is one of the most stable cathodes because of its stable structure and strong bonding between P and O. However, it has a lower energy density than lithium transition metal oxides. To investigate the high energy density of phosphate materials, vanadium phosphates were investigated. Vanadium enables multiple redox reactions as well as high redox potentials. LiVPO4O has two redox reactions (V5+/V4+/V3+) but low electrochemical activity. In this study, LiVPO4O is doped with fluorine to improve its electrochemical activity and increase its operational redox potential. With increasing fluorine content in LiVPO4O1-xFx, the local vanadium structure changed as the vanadium oxidation state changed. In addition, the operating potential increased with increasing fluorine content. Thus, it was confirmed that fluorine doping leads to a strong inductive effect and high operating voltage, which helps improve the energy density of the cathode materials.
        4,000원
        45.
        2023.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Amorphous In-Ga-Zn-O (a-IGZO) thin film transistors (TFTs) with a coplanar structure were fabricated to investigate the feasibility of their potential application in large size organic light emitting diodes (OLEDs). Drain currents, used as functions of the gate voltages for the TFTs, showed the output currents had slight differences in the saturation region, just as the output currents of the etch stopper TFTs did. The maximum difference in the threshold voltages of the In-Ga-Zn-O (a-IGZO) TFTs was as small as approximately 0.57 V. After the application of a positive bias voltage stress for 50,000 s, the values of the threshold voltage of the coplanar structure TFTs were only slightly shifted, by 0.18 V, indicative of their stability. The coplanar structure TFTs were embedded in OLEDs and exhibited a maximum luminance as large as 500 nits, and their color gamut satisfied 99 % of the digital cinema initiatives, confirming their suitability for large size and high resolution OLEDs. Further, the image density of large-size OLEDs embedded with the coplanar structure TFTs was significantly enhanced compared with OLEDs embedded with conventional TFTs.
        4,000원
        46.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Lead-free perovskite ceramics, which have excellent energy storage capabilities, are attracting attention owing to their high power density and rapid charge-discharge speed. Given that the energy-storage properties of perovskite ceramic capacitors are significantly improved by doping with various elements, modifying their chemical compositions is a fundamental strategy. This study investigated the effect of Zn doping on the microstructure and energy storage performance of potassium sodium niobate (KNN)-based ceramics. Two types of powders and their corresponding ceramics with compositions of (1-x)(K,Na)NbO3-xBi(Ni2/3Ta1/3)O3 (KNN-BNT) and (1-x)(K,Na)NbO3-xBi(Ni1/3Zn1/3Ta1/3) O3 (KNN-BNZT) were prepared via solid-state reactions. The results indicate that Zn doping retards grain growth, resulting in smaller grain sizes in Zn-doped KNN-BNZT than in KNN-BNT ceramics. Moreover, the Zn-doped KNNBNZT ceramics exhibited superior energy storage density and efficiency across all x values. Notably, 0.9KNN-0.1BNZT ceramics demonstrate an energy storage density and efficiency of 0.24 J/cm3 and 96%, respectively. These ceramics also exhibited excellent temperature and frequency stability. This study provides valuable insights into the design of KNNbased ceramic capacitors with enhanced energy storage capabilities through doping strategies.
        4,000원
        47.
        2023.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        This article presents the crucial role played by the French underground research laboratory (URL) in initiating the deep geological repository project Cigéo. In January 2023, Andra finalized the license application for the initial construction of Cigéo. Depending on Government’s decision, the construction of Cigéo may be authorized around 2027. Cigéo is the result of a National program, launched in 1991, aiming to safely manage high-level and intermediate level long-lived radioactive wastes. This National program is based on four principles: 1) excellent science and technical knowledge, 2) safety and security as primary goals for waste management, 3) high requirements for environment protection, 4) transparent and openpublic exchanges preceding the democratic decisions and orientations by the Parliament. The research and development (R&D) activities carried out in the URL supported the design and the safety demonstration of the Cigéo project. Moreover, running the URL has provided an opportunity to gain practical experience with regard to the security of underground operations, assessment of environmental impacts, and involvement of the public in the preparation of decisions. The practices implemented have helped gradually build confidence in the Cigéo project.
        4,600원
        48.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, Ni-Y2O3 powder was prepared by alloying recomposition oxidation sintering (AROS), solution combustion synthesis (SCS), and conventional mechanical alloying (MA). The microstructure and mechanical properties of the alloys were investigated by spark plasma sintering (SPS). Among the Ni-Y2O3 powders synthesized by the three methods, the AROS powder had approximately 5 nm of Y2O3 crystals uniformly distributed within the Ni particles, whereas the SCS powder contained a mixture of Ni and Y2O3 nanoparticles, and the MA powder formed small Y2O3 crystals on the surface of large Ni particles by milling the mixture of Ni and Y2O3. The average grain size of Y2O3 in the sintered alloys was approximately 15 nm, with the AROS sinter having the smallest, followed by the SCS sinter at 18 nm, and the MA sinter at 22 nm. The yield strength (YS) of the SCS- and MA-sintered alloys were 1511 and 1688 MPa, respectively, which are lower than the YS value of 1697 MPa for the AROS-sintered alloys. The AROS alloy exhibited improved strength compared to the alloys fabricated by SCS and conventional MA methods, primarily because of the increased strengthening from the finer Y2O3 particles and Ni grains.
        4,000원
        49.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        UV and O3 are materials used in the water treatment process, and many studies have been reported to remove organic matters, contaminants, and microorganisms. In this study, we were investigated effects of Chirnomidae (Chironomus flaviplumus, Chironomus riparius), which are contamination indicator species to exposure UV and O3 for the survival rate, body color change and gene expression response. The survival rate of C. flaviplumus exposed to UV decreased to about 70% after 24 hours, and C. riparius about 50%. There was no change in the survival rate of C. flaviplumus exposed to O3, and C. riparius decreased to 95% after 10 minutes of exposure, but there was no change during the subsequent exposure time. In addition, UV and O3 exposure to the two species in body color faded in a time-dependent. In the HSP70 gene expression, C. riparius showed an increase in expression after UV exposure compared to the control group, and a significant difference was shown 12 hours after exposure (P<0.05). C. flaviplumus exposed to O3 showed a relatively low expression compared to the control group, and showed a significant difference at 10 minutes and 1 hour after exposure (P<0.05). These results reported the ecotoxicological effects on Chironomidae according to UV and O3 exposure. Therefore, the results of this study can be used as basic data to understand the effects of UV and O3, which are disinfectants used in water treatment plants, on Chirnomidae entering plants. Key words: Chironomus flaviplumus, Chironomus riparius, UV, O3, acute toxicity, survival
        4,000원
        50.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, a THC removal system was developed using an oxidation catalyst to solve the problems of the existing thermal oxidation methods, RTO and RCO. In addition, this system was applied to industrial sites to confirm the VOCs removal efficiency. As a result of testing to remove THC and VOCs by applying the reaction system for THC removal in industrial sites, the THC removal efficiency range is between 99.5% and 99.9%. The treatment efficiency of individual VOCs treated through this system was the lowest at 79.0% for methylethylketone and the highest at 91.3% for acetaldehyde, and the average treatment efficiency was about 85.4%. From these numbers, the performance was superior to the existing RTO and RCO systems that showed THC removal performance. This is due to the fact that the oxidation reaction of the oxidation catalyst is a very fast catalyst surface reaction, and the characteristics of the catalytic oxidation reaction are complete oxidation and oxidation reaction under rarefied conditions. In this study, the catalyst role in the reaction system for THC removal is to process THC simultaneously with the system heat source. This is believed to be because the reaction of the oxidation catalyst is a strongly exothermic reaction and can sufficiently provide the amount of heat necessary for the system. At the same time, an oxidation reaction that breaks the bonds of the THC component also occurs. This reaction is a strong exothermic reaction, which can help the system maintain a high temperature during the reaction, and is considered an effective system for processing high concentrations of THC in actual industrial sites where THC concentrations are high, as in this study.
        4,000원
        51.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        백합 종간 교잡종은 다양한 교배 방법에 의해 생산되어지 고 있다. 그러나 이들 종간 교잡종은 대부분 불임이다. 2n gametes는 백합에서 종간 교잡종 F1의 불임을 극복할 수 있 을 뿐 아니라 우수한 유전형질을 지닌 2n과의 교배에 이용할 수 있고 후대 다양한 유전형질을 기대할 수 있다. 따라서 본 실험에서는 가장 효과적으로 2n gametes를 생산할 수 있는 방법을 구축하기 위하여 백합 Oriental hybrids ‘Medusa’와 ‘Marco Polo’에 N2O를 처리하였다. 같은 Oriental 그룹 내 에서도 ‘Medusa’와 ‘Marco Polo’는 화뢰 크기별 감수분열 시기가 달랐다. 감수분열 tetrad 시기에 염색체를 관찰한 결 과 sequential spindles, tripolar spindles에 의해 2가지 다른 형태가 관찰되었다. ‘Medusa’에서 2atm의 N2O를 처리 한 화뢰 길이 10~15mm와 20~25mm에서 monad, dyad, triad, tetrad가 관찰되었다. 그러나 4atm에서는 tetrad 이외에는 검경 되지 않았다. ‘Marco polo’의 경우 화뢰 길 이 10~15mm, 25~30mm 시기에 2, 4atm의 N2O를 12, 24 시간 동안 처리한 구에서 모두 dyad, triad가 관찰되었다. ‘Medusa’, ‘Marco Polo’ 모두 dyad, triad, tetrad가 관찰 된 시기는 대조구에서 interphase와 metaphase Ⅰ에 해당 하는 시기이다. 화분의 모양은 타원형으로 처리 전·후 변화가 없었으며 처리 후 화분의 크기는 n 보다 큰 화분뿐 아니라 작 은 화분도 관찰되어 전체적으로 다양했다. 화분의 임성과 발 아율은 처리구별로 차이가 없었으나 평균적으로 처리 후가 무처리구보다 임성은 약 10%, 발아는 약 20% 정도 떨어졌다. ‘Medusa’와 ‘Marco Polo’를 이용하여 N2O를 처리한 것과 처리하지 않은 것을 정역 교배하였을 때 자방이 비대 되는 형 태가 2가지이었으나 처리 별 차이는 아니었다. 획득된 식물체 를 Flow cytometry로 검정한 결과, 무처리 ‘Marco Polo’와 2atm 24시간 32mm에 처리한 ‘Medusa’의 교배를 통해 하 나의 식물체에서 2배체와 3배체가 모두 나오는 mixoploid를 확인할 수 있었다. 그 외 실험을 통해 얻은 식물체 중에서 이 수체가 4개 발견되었다. 확실한 3배체를 가진 식물체는 관찰 할 수 없었다.
        4,500원
        52.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구는 대한민국 울릉도 특산식물인 추산쑥부쟁이(Aster × chusanensis Y.S.Lim, Hyun, Y.D.Kim & H.C.Shin)의 기내 대량증식체계 확립을 위해 시토키닌 계열 식물생장조절 제를 첨가하여 캘러스 및 신초 형성 조건을 구명하고자 수행 하였다. 실험결과, 추산쑥부쟁이의 줄기 절편체에서 캘러스 와 신초가 형성되었다. 캘러스 형성률은 TDZ 3.0mg·L-1처 리구에서 88.9%로 가장 높았고 BAP 3.0mg·L-1와 Zeatin 3.0mg·L-1 처리구는 66.7%, 2iP 3.0mg·L-1 처리구에서는 11.1%였다. 신초 형성률은 모든 처리구에서 77% 이상이고 특히 TDZ처리구와 Zeatin 처리구에서 100%였다. 그러나 TDZ처리구에서는 형성된 신초가 부풀어 오르거나, 잎에 과수 성이 나타나는 등 형태적 기형이 나타났다. Zeatin처리구에 서 발생한 신초는 정상적인 형태를 나타났다. 잎 절편체에서 는 캘러스, 신초가 발생하지 않았으며 절편체가 탈색하며 고 사하는 것을 확인하였다. 종합적으로 추산쑥부쟁이의 캘러 스 및 신초 형성을 위해서는 줄기 절편체를 배양 재료로 이 용하는 것이 효과적으로 확인되었다. 캘러스 유도에는 TDZ 3.0mg·L-1처리가 가장 효과적이었고, 추후 NAA와 같은 옥신 을 함께 첨가하여 증식 효과를 분석하는 연구가 필요할 것이 다. 또한, 신초 유도에도 TDZ 3.0mg·L-1 처리가 효과적이었 으나 장기간, 고농도로 사용할 경우 형태적인 기형이 발생할 수 있어 정상적인 식물생산에 부적합한 것으로 확인되었다. 따라서 형태적 기형이 발생하지 않은 아데닌 유도체형 시토키 닌인 Zeatin을 활용하는 것을 추천한다. 본 연구는 울릉도 특 산식물인 추산쑥부쟁이의 기내 대량증식과 생태계 유지에 필 요한 종 공급을 위한 대량증식 체계 구축을 위한 자료로 활용 할 수 있을 것이다.
        4,000원
        53.
        2023.11 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        The effects of La3+ substitution for Sr2+-site on the crystal structure and the dielectric properties of (Ba0.7Sr0.3-3x/2Lax) (Ti0.9Zr0.1)O3 (BSLTZ) (0.005 ≤ x ≤ 0.02) ceramics were investigated. The structural characteristics of the BSLTZ ceramics were quantitatively evaluated using the Rietveld refinement method from X-ray diffraction (XRD) data. For the specimens sintered at 1,550 °C for 6 h, a single phase with a perovskite structure and homogeneous microstructure were observed for the entire range of compositions. With increasing La3+ substitution (x), the unit cell volume decreased because the ionic size of La3+ (1.36 Å) ions is smaller than that of Sr2+ (1.44 Å) ions. With increasing La3+ substitution (x), the tetragonal phase fraction increased due to the A-site cation size mismatch effect. Dielectric constant (εr) increased with the La3+ substitution (x) due to the increase in tetragonality (c/a) and the average B-site bond valence of the ABO3 perovskite. The BSLTZ ceramics showed a higher dielectric loss due to the smaller grain size than that of (Ba0.7Sr0.3)(Ti0.9Zr0.1)O3 ceramics. BSLTZ (x = 0.02) ceramics met the X7R specification proposed by the Electronic Industries Association (EIA).
        4,000원
        54.
        2023.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study investigates the influence of the type of lipid phase (corn oil [CO], palm oil [PO], MCT oil [MO], lemon oil [LO]) on the physical characteristics and bioactive peptide (BP) encapsulation in food-grade water-in-oil-in-water (W/O/W) double emulsions. The stabilities of the double emulsions were analyzed for droplet size characteristics, viscosity, dynamic rheological properties, encapsulation efficiency (EE), and release rate of BP (at different temperatures: 4, 25, 37, and 60oC) for 28 days. The encapsulated BP acts as an active substance in the osmotic balance and destabilization of the double emulsion system. For the effect of the oil phase, double emulsions prepared with PO showed the best droplet stability without phase separation (D50 < 1 m) and high BP retention (EE > 60%). In the release rate at high temperatures (60oC), the BP released from double emulsions was in the order of MO > CO > LO > PO over time. In contrast, the BP release from double emulsions at low temperatures (< 37oC) had no difference depending on the oil type. Therefore, the information obtained from this work is useful for preparing stable, functional food or cosmetic products from double emulsions using a BP.
        4,000원
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