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        검색결과 34

        1.
        2024.01 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Photoanode optimization is a fascinating technique for enlightening the power conversion efficiency (PCE) of dye-sensitized solar cells (DSSCs). In this present study, V2O5/ ZnO and reduced graphene oxide (rGO)-V2O5/ZnO nanocomposites (NCs) were prepared by the solid-state technique and used as photoanodes for DSSCs. A wet chemical technique was implemented to generate individual V2O5 and ZnO nanoparticles (NPs). The structural characteristics of the as-synthesized NCs were investigated and confirmed using powder X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), and Scanning electron microscope (SEM) with energy dispersive X-ray (EDX) analysis. The average crystallite size (D) of the as-synthesized V2O5/ ZnO and rGO-V2O5/ZnO NCs was determined by Debye-Scherer’s formula. The bandgap (eV) energy was calculated from Tauc’s plots, and the bonding nature and detection of the excitation of electrons were investigated using the Ultra violet (UV) visible spectra, Fourier Transform infrared (FTIR) and photoluminescence (PL) spectral analysis. Electrical studies like Hall effect analysis and the Nyquist plots are also described. The V2O5/ ZnO and rGO-V2O5/ZnO NCs based DSSCs exhibited 0.64% and 1.27% of PCE and the short circuit current densities and open circuit voltages improved from 7.10 to 11.28 mA/cm2 and from 0.57 to 0.68 V, respectively.
        4,300원
        2.
        2023.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Rechargeable zinc-based batteries (RZBs) with the advantages of high safety, low cost, abundant resources and environmental friendliness, are considered as advanced secondary battery systems that can be applied to large-scale energy storage. As an important cathode material for RZBs, NASICON-type Na3V2( PO4)3 (NVP) possesses three-dimensional and large-scale ion channels that facilitate the rapid diffusion of Zn2+, and has a higher average operating voltage compared with other vanadiumbased compounds, thus exhibiting the possibility of realizing RZBs with high energy density. However, NVP still has some problems, such as poor electronic conductivity and spontaneous dissolution in aqueous solution. The sluggish kinetics of Zn2+ (de)intercalation in NVP and dendritic growth on the Zn anode also contribute to the poor rate performance and short cycle life of the batteries. In this review, optimization strategies for the electrochemical performance of RZBs with NVP as cathode are systematically elaborated, including modification of NVP cathode and optimization of electrolyte. Several mainstream energy storage mechanisms and analysis methods in this battery system are sorted out and summarized. On this basis, the development direction of NVP–RZB system is further prospected.
        6,100원
        4.
        2022.11 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        For the selective catalytic reduction of NOx with ammonia (NH3-SCR), a V2O5WO3/TiO2 (VW/nTi) catalyst was prepared using V2O5 and WO3 on a nanodispersed TiO2 (nTi) support by simple impregnation process. The nTi support was dispersed for 0~3 hrs under controlled bead-milling in ethanol. The average particle size (D50) of nTi was reduced from 582 nm to 93 nm depending on the milling time. The NOx activity of these catalysts with maximum temperature shift was influenced by the dispersion of the TiO2. For the V0.5W2/nTi-0h catalyst, prepared with 582 nm nTi-0h before milling, the decomposition temperature with over 94 % NOx conversion had a narrow temperature window, within the range of 365-391 °C. Similarly, the V0.5W2/nTi-2h catalyst, prepared with 107 nm nTi-2h bead-milled for 2hrs, showed a broad temperature window in the range of 358~450 °C. However, the V0.5W2/Ti catalyst (D50 = 2.4 μm, aqueous, without milling) was observed at 325-385 °C. Our results could pave the way for the production of effective NOx decomposition catalysts with a higher temperature range. This approach is also better at facilitating the dispersion on the support material. NH3-TPD, H2-TPR, FT-IR, and XPS were used to investigate the role of nTi in the DeNOx catalyst.
        4,300원
        5.
        2022.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        When the CP voltage is disconnected, the measured voltage on the ICCB side is measured to be 12V, and the voltage on the OBC side is measured to be 0V. When the PD signal was disconnected, the ICCB-side measured voltage was 0V and the OBC-side measured voltage was 4.5V. From this, disconnected position be found with the voltage value measured. When CP was disconnected for a short time, the PD voltage did not change to 1.5V, and when the PD was disconnected, the CP signal and PD signal changed to 9V, and if the CP and PD voltages were normal, the charge control could be performed normally.
        4,000원
        6.
        2021.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, the Euro NCAP-based AEB system evaluation simulation was conducted by applying the calculated corrected TTC by road condition estimation of scenarios (CPFA, CPNC, CPLA) of the V2P situation scenario using PC-Crash, a program used for traffic accident analysis. The scenario was evaluated in consideration of the two road conditions. the low-speed conditions among every scenarios avoided collision, but in the medium and high-speed conditions has been collided with pedestrian. It was confirmed that the time point at recognizing pedestrian was lower than set TTC at which AEB system was operated, even though the AEB was operated immediately, a collision occurred due to insufficient braking distance. As in this study, if studies such as V2V, V2P, and V2B considering road friction are actively conducted, it is expected to be useful data for automobile accident prevention and accident analysis.
        4,000원
        7.
        2021.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        “Zhe” in the structure of “V1 zhe V2” in the Chinese translation of Qingwen Zhiyao is a counter translation of the Manchu adverb affix “- me” “- fi” “- hai, - hei, - hoi”. There are some special uses of this structure in Chinese translation, such as the combination of the tentative state and the continuous marker “zhe”, and the non continuous verb enters the “V1 zhe V2” structure as V1. The reason is that it is influenced by Manchu. The interference characteristics of Manchu language are weakened in the adaptation of Qingwen Zhiyao. By investigating the literature of the Qing Dynasty, it is found that the usage influenced by Manchu such as “Xiang zhe qiao” and “Zhuo liang zhe” once entered Chinese in the Qing Dynasty, and disappeared in modern Chinese with the decline of Manchu. The Chinese version has traces of Southern Mandarin, and the adapted version reflects the characteristics of Beijing Mandarin. The principle of iconicity has different constraints on the word order of verb conjunction in Manchu and Chinese. The text adaptation follows the law of sentence pattern development and reflects the prescriptive direction of Chinese sentence pattern development. Language contact affects the development of relevant sentence patterns to a certain extent, but it is ultimately restricted by the law of Chinese itself.
        7,800원
        8.
        2021.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, the AEB system evaluation simulation was conducted by applying a corrected TTC from 0s to 3s obtained by estimating the road-friction factor and slope applying two scenarios(CCRs and CCRm) that may occur in V2V situation using PC-CrashⓇ, a program used for traffic accident analysis. As a result of two scenarios : At 0.8 of road-friction factor and 0° slope which adapted default model of TTC had longer braking distance so that it crashed. At 0.2 of road-friction factor with corrected TTC slidingly crashed due to slope and braking condition. CCRs and CCRm scenario showed that the maximum slipped distance of the collision avoidance situation was 31.7m, 87.7m. And the collision speed was 35.7km/h at 50km/h and 66.1km/h at 80km/h.
        4,000원
        9.
        2019.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        This study describes the doping effect of Yb2O3 on microstructure, electrical and dielectric properties of ZnO-V2O5- MnO2-Nb2O5 (ZVMN) ceramic semiconductors sintered at a temperature as low as 900°C. As the doping content of Yb2O3 increases, the ceramic density slightly increases from 5.50 to 5.54 g/cm3; also, the average ZnO grain size is in the range of 5.3-5.6 μm. The switching voltage increases from 4,874 to 5,494 V/cm when the doping content of Yb2O3 is less than 0.1 mol%, whereas further doping decreases this value. The ZVMN ceramic semiconductors doped with 0.1 mol% Yb2O3 reveal an excellent nonohmic coefficient as high as 70. The donor density of ZnO gain increases in the range of 2.46-7.41×1017 cm−3 with increasing doping content of Yb2O3 and the potential barrier height and surface state density at the grain boundaries exhibits a maximum value (1.25 eV) at 0.1 mol%. The dielectric constant (at 1 kHz) decreases from 592.7 to 501.4 until the doping content of Yb2O3 reaches 0.1 mol%, whereas further doping increases it. The value of tanδ increases from 0.209 to 0.268 with the doping content of Yb2O3.
        4,000원
        10.
        2019.09 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Spherical Li3V2(PO4)3 (LVP) and carbon-coated LVP with a monoclinic phase for the cathode materials are synthesized by a hydrothermal method using N2H4 as the reducing agent and saccharose as the carbon source. The results show that single phase monoclinic LVP without impurity phases such as LiV(P2O7), Li(VO)(PO4) and Li3(PO4) can be obtained after calcination at 800 oC for 4 h. SEM and TEM images show that the particle sizes are 0.5~2 μm and the thickness of the amorphous carbon layer is approximately 3~4 nm. CV curves for the test cell are recorded in the potential ranges of 3.0~4.3 V and 3.0~4.8 V at a scan rate of 0.01 mV s–1 and at room temperature. At potentials between 3.0 and 4.8 V, the third Li+ ions from the carbon-coated LVP can be completely extracted, at voltages close to 4.51 V. The carbon-coated LVP exhibits an initial specific discharge capacity of 118 mAh g–1 in the voltage region of 3.0 to 4.3 V at a current rate of 0.2 C. The results indicate that the reducing agent and carbon source can affect the crystal structure and electrochemical properties of the cathode materials.
        4,000원
        12.
        2019.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        경계성(界性)이란 인류가 객관세계 사물의 경계(Boundary)를 인식하는 한 방식으로 유경계성(有界, boundary)과 무경계성(無界,unboundary)으로 분리된다. 인지적 경험에 근거하여 사물에 대한 ‘경계 설정’이 가능하면 그 사물은 유경계성을 띠고, 이 ‘경계 설정’이 불가능하다면 그 사물은 무경계성을 띤다. 인지언어학자들은 경계성 이론을 언어현상에 응용하여 설명하기 시작하였는데 본 연구는 이러한 언어현상의 경계성 이론에 입각하여 중국어 사동문법의 인지적 분석에 응용해 보았다. 특별히 현재 상용되고 있는 다양한 중국어 사동형태 가운데 그 형식상 동일한 유형의 사동구조로 취급되고 있는 ‘NP1+VP+NP2’ 구조와 ‘NP1+VP(‘V1V2’) +NP2’ 즉, 결과보어 사동구조에 착안하여 구조상 존재하는 문법적 차이를 근거로 ‘VP’와 ‘V1V2’가 술어로서 한정짓게 되는 경계성의 차이를 탐구하였다. 아울러 NP2와 了의 수반으로 인해 경계화 짓는 특성 및 자질이 어떻게 나타나는지 인지적 분석으로 접근하였다.
        5,400원
        13.
        2019.03 구독 인증기관 무료, 개인회원 유료
        4,000원
        14.
        2016.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We have investigated a glass-forming region of V2O5- P2O5-ZnO glass and the effects of the addition of modifier oxides (B2O3) to the glass systems as a sealing material to improve the adhesion between the glass frits and a soda lime substrate. Thermal properties and coefficient of thermal expansion were measured using a differential scanning calorimetry, a dilatometer and a hot stage microscopy. Structural changes and interfacial reactions between the glass substrate and the glass frit after sintering (at 400 oC for 1 h) were measured by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscope. The results showed that the adhesion strength increases as the content of B2O3 at 5 mol% increases because of changes in the structural properties. It seems that the glass structures change with B2O3, and the Si4+ ions from the substrate are diffused to the sealing glass. From these results, we could understand the mechanism of strengthening of the adhesion of soda lime silica substrate by ion-diffusion from the substrate to the glass.
        4,000원
        15.
        2013.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study describes the amendment of Durbin's k-∈-v2-f model and its application to turbulent channel flow to test the model’s performance. Modeling redistribution and dissipation rate terms for the scalar v2 transport equation is considered by the elliptic blending equation which is used in the second moment closure generally. The prediction results are directly compared to the DNS and Durbin's original k-∈-v2-f model to assess the performance of the new model predictions and to show their reasonable agreement with the DNS and Durbin's model for all the flow characteristics that are analyzed for the present study.
        4,000원
        16.
        2010.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        For the aim of low-temperature co-fired ceramic microwave components, sintering behavior and microwave properties (dielectric constant , quality factor Q, and temperature coefficient of resonant frequency ) are investigated in [BCZN] ceramics with addition of . The specimens are prepared by conventional ceramic processing technique. As the main result, it is demonstrated that the additives () show the effect of lowering of sintering temperature and improvement of microwave properties at the optimum additive content. The addition of 0.25 wt% lowers the sintering temperature to utilizing liquidphase sintering and show the microwave dielectric properties (dielectric constant = 75, quality factor = 572 GHz, temperature coefficient of resonance frequency ). The estimated microwave dielectric properties with addition (increase of , decrease of , shift of to negative values) can be explained by the observed microstrucure (sintered density, abnormal grain structure) and possibly high-permittivity (BZN) phase determined by X-ray diffraction.
        4,000원
        17.
        2009.11 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We designed new compositions for lead free and low temperature sealing glass frit of ZnO-V2O5-P2O5 system, which can be used for PDP (Plasma Display Panel) or other electronic devices. The ZnO-V2O5-P2O5 system can be used as a sealing material at temperatures even lower than 430˚C. This system, however, showed lower bonding strength with glass substrate compared to commercialized Pb based sealing materials. So, we added TiO2 as a promoter for bonding strength. We examined the effect of TiO2 addition on sealing behaviors of ZnO-V2O5-P2O5 glasses with the data for flow button, wetting angle, temporary & permanent residual stress of glass substrate, EPMA analysis of interface between sealing materials and glass substrate, and bonding strength. As a result, sealing characteristics of ZnO-V2O5-P2O5 system glasses were improved with TiO2 addition, but showed a maximum value at 5 mol% TiO2 addition. The reason for improved bonding characteristics was considered to be the chemical interaction between glass substrate and sealing glass, and structural densification of sealing glass itself.
        4,000원
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