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        검색결과 743

        102.
        2020.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Free-standing hybridized electrode consisting of double-walled carbon nanotubes (DWNTs) and activated carbon have been fabricated for flexible supercapacitor applications. The xanthan-gum, used in our methodology, showed high ability in dispersing the strongly bundled DWNTs, and was then effectively converted to activated carbon with large surface area via chemical activation. The homogeneously dispersed DWNTs within xanthan-gum derived activated carbon acted as both electrical path and mechanical support of electrode material. The hybridized film from highly dispersed DWNTs and activated carbon was mechanically strong, has high electrical conductivity, and exhibited high specific capacitance of 141.5 F/g at the current density of 100 mV/s. Our hybridized film is highly promising as electrode material for flexible supercapacitors in wearable device.
        4,000원
        103.
        2020.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        토마토와 박과류채소의 유기농산물을 생산하기 위하여 무농약으로 재배하는 시설하우스에서 최근 문제되는 병해를 조사한 결과 토마토 잎곰팡이병과 토마토반점위조바이러스병, 토마토퇴록바이러스병, 박과류 쥬키니황화모자이크바이러스병, 박과류 흰가루병 등의 피해가 심한 것으로 조사되었다. 농약을 사용하여 일반재배를 하는 시설하우스에 비해 무농약재배 하우스에서 재배되는 작물에서 병 발생 시기가 더 빠르고 병 발생도 심한 것으로 나타났으며, 총채벌레와 진딧물 등에 의해 매개되는 바이러스병 피해가 심한 것으로 조사되었다. 따라서 우수한 유기농산물을 생산하기 위해서는 병해충방제를 효율적으로 하는 것이 중요하며, 병 발생 피해를 최소화기 위해서는 포장위생과 물리적 차단, 유기농업자재나 미생물제 등을 종합적으로 활용하여 예방적으로 방제하는 것이 가장 중요하다.
        4,000원
        104.
        2020.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        China Pilot Free Trade Zone is a "policy practice zone," and China has already established 18 pilot FTZs since the approval of Shanghai Pilot FTZ in Sept. 2013. Pilot FTZs have become high grounds for Chinese economic reform through 'optimization of business environment', 'facilitation of investment & trade', and 'policy innovation in various fields such as financial services and real economy.' Construction of pilot FTZ has aggressively extended national strategies such as active service, construction of "One Belt, One Road" Initiative, cooperative development of Jingjinji Metropolitan region (Beijin-Tianjin-Hebei), integrated development of Yangtze River Delta Economic Zone, and revitalization of northeast China, etc. as well as collaboration with surrounding nations. Recent entry of new stage of China-Korea relations has great potential of complementary cooperation. As a "policy practice zone" of Chinese economic reform, Pilot FTZs have arranged business environment facilitated with legislation and internationalization, regulation system suitable for international trade-investment rules, and open financial environment through system innovation & reform in various fields such as investment, trade, and finance, etc. This is giving a new motivation for higher level and broadened area of China-Korea economic relations.
        4,800원
        105.
        2020.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 논문은 자발적 지리정보인 오픈스트리트맵(OpenStreetMap, OSM)을 활용하여 중학교 자유학기제의 지도 수업과 학생 활동을 분석한 연구이다. 본 연구를 통해 지도 수정과 편집이 자유로운 오픈스트리트맵을 활용하여 학생들이 직접 지도 편집을 수행하고 중학교 자유학기제 수업에 적용할 수 있는 학생 활동 및 수행 평가 내용을 제안하였다. 이를 위해 총 8차시의 주제선택 활동을 계획하였고, 지형지물의 위치, 굴곡, 형태, 크기, 면적에 대해 학생들은 점, 선, 면의 지도 기호를 사용하여 지도 입력과 수정. 편집 활동을 진행하였다. 학생 활동 평가를 위해 학생들의 지도 정보 입력 및 편집 활동 결과 내용을 분석하고 이를 다섯 단계의 지도 습득 수준으로 분류하여 각 활동 수준의 특성을 살펴보았다. 이러한 논의를 바탕으로 본 연구는 인터넷 지도와 모바일 기기의 지도 활용 환경을 감안하여 학생 주도의 디지털 지도 학습과 지도 교육 관련 연구의 필요성을 제기하고자 한다.
        4,300원
        109.
        2020.07 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        NKN [(Na,K)NbO3] is a candidate lead-free piezoelectric material to replace PZT [Pb(Zr,Ti)O3]. A single crystal has excellent piezoelectric-properties and its properties are dependent of the crystal orientation direction. However, it is hard to fabricate a single crystal with stoichiometrically stable composition due to volatilization of sodium during the growth process. To solve this problem, a solid solution composition is designed (Na,K)NbO3-Ba(Cu,Nb)O3 and solid state grain growth is studied for a sizable single crystal. Ceramic powders of (Na,K)NbO3-M(Cu,Nb)O3 (M = Ca, Sr, Ba) are synthesized and grain growth behavior is investigated for different temperatures and times. Average normal grain sizes of individual specimens, which are heat-treated at 1,125 oC for 10 h, are 6.9, 2.8, and 1.6 m for M = Ca, Sr, and Ba, respectively. Depending on M, the distortion of NKN structure can be altered. XRD results show that (NKN-CaCuN: shrunken orthorhombic; NKN-SrCuN: orthorhombic; NKN-BaCuN: cubic). For the sample heat-treated at 1,125 oC for 10 h, the maximum grain sizes of individual specimens are measured as 40, 5, and 4,000 m for M = Ca, Sr, and Ba, respectively. This abnormal grain size is related to the partial melting temperature (NKN-CaCuN: 960 oC; NKN-SrCuN: 971 oC; NKN-BaCuN: 945 oC).
        4,000원
        112.
        2020.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Objectives: Free Water Protocols (FWPs) are implemented selectively because of mixed evidence on the benefits associated with their use. This retrospective study examines the implementation a long-standing clinical program and descriptively reports rehabilitation and quality care outcomes. Methods: Data were collected over 6 years (n = 575). Inpatient rehabilitation setting. Variables included in this study were age, medical diagnoses, rate of acute care hospital transfers, discharge destinations, length of time on FWP. Results: Cohort consisted of older adults (M = 68.43, SD = 15.11), with diagnosis of stroke (60.2%), brain injury (19.1%), spinal cord injury (7.3%), cardiac (1%), orthopedics (5%), other (13.1%). Acute care hospital transfers occurred in 6% as descriptively compared to national average (14%). Additionally, participants tolerated FWP for days (M = 14.1, SD = 14.4) and most went home following rehabilitation Discussion: This retrospective study concludes the feasibility of implementing a FWP in a rehabilitation facility and reports descriptive outcomes. Experimental research is required for conclusions to be made regarding effectiveness of the FWP for dysphagia.
        4,000원
        113.
        2020.06 구독 인증기관 무료, 개인회원 유료
        3,000원
        114.
        2020.06 KCI 등재후보 구독 인증기관 무료, 개인회원 유료
        2-브로모에틸 에틸 에테르를 이용한 2-에티닐피리딘의 무촉매 중합을 통하여 측쇄에 에테르 부분을 갖는 새로운 공액구조 고분자를 합성하였다. 이 중합반응은 비교적 낮은 온도 조건에서도 균일하게 잘 진행 되었으며 89%의 수율로 해당 고분자를 합성할 수 있었다. NMR, IR, UV-visible 분광분석기 등을 이용하여 고 분자의 구조를 분석한 결과 설계한 치환기를 갖는 해당 고분자가 합성되었음을 확인할 수 있었다. 본 고분자는 물을 포함한 DMF, DMSO, DMAc, 메탄올 등의 유기 용매에 완전히 용해하였다. 합성 고분자의 전기화학적 특성과 광발광 특성을 측정하고 분석하였다.
        4,000원
        115.
        2020.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this paper, the dynamic snapping of the 3-free-nodes spatial truss model was studied. A governing equation was derived considering geometric nonlinearity, and a model with various conditions was analyzed using the fourth order Runge-Kutta method. The dynamic buckling phenomenon was observed in consideration of sensitive changes to the force mode and the initial condition. In addition, the critical load level was analyzed. According to the results of the study, the level of critical buckling load elevated when the shape parameter was high. Parallelly, the same result was caused by the damping term. The sensitive asymmetrical changes showed complex orbits in the phase space, and the critical load level was also becoming lowly. In addition, as the value of damping constant was high, the level of critical load also increases. In particular, the larger the damping constant, the faster it converges to the equilibrium point, and the occurrence of snapping was suppressed.
        4,000원
        116.
        2020.05 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        The design and fabrication of catalysts with low-cost and high electrocatalytic activity for the oxygen evolution reaction (OER) have remained challenging because of the sluggish kinetics of this reaction. The key to the pursuit of efficient electrocatalysts is to design them with high surface area and more active sites. In this work, we have successfully synthesized a highly stable and active NiCo2S4 nanowire array on a Ni-foam substrate (NiCo2S4 NW/NF) via a two-step hydrothermal synthesis approach. This NiCo2S4 NW/NF exhibits overpotential as low as 275 mV, delivering a current density of 20 mA cm-2 (versus reversible hydrogen electrode) with a low Tafel slope of 89 mV dec-1 and superior long-term stability for 20 h in 1M KOH electrolyte. The outstanding performance is ascribed to the inherent activity of the binder-free deposited, vertically aligned nanowire structure, which provides a large number of electrochemically active surface sites, accelerating electron transfer, and simultaneously enhancing the diffusion of electrolyte.
        4,000원
        117.
        2020.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Carbon materials with tailorable structures and superior properties have great potential applications in environmental protection, energy conversion, and catalysis. Plant biomass as abundant and green non-toxic raw materials has been considered as good precursors for synthesizing heteroatom-doped carbon materials. However, few studies have been reported on the different natures of carbon materials derived from different parts of the same plant biomass. In this study, we prepared carbon materials from the petioles and blades of apricot leaves by direct pyrolysis without additives. Detailed characterizations indicate that these two carbon materials are similar in element composition and graphitization degree, but differ greatly in surface area and pore volume. These differences can be attributed to the different contents of inorganic salts, vascular bundles, and proteins in petioles and blades. When used as catalysts for the oxidation of ethylbenzene, the petiole-derived carbon shows better catalytic performance than the blades derived carbon due to its high surface area, large average pore size, and doped nitrogen atoms. Furthermore, the carbon catalysts derived from the petioles and blades of poplar leaves and parasol tree leaves show the same difference in catalytic reaction, implying that the above-mentioned conclusion is rather universal, which can provide reference for the synthesis of carbon materials from leaves.
        4,000원
        118.
        2020.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        지구상에서 가장 오래된 해양 미세조류로 알려진 스피룰리나는 인체에 필요한 영양성분을 대부분 함유하고 있는 것으로 알려져 있다. 그 구성성분으로는 phycocyanin, chlorophyll, β-carotene과 같 은 다양한 물질을 다량 함유한다고 보고되고 있으며, 노화 및 미백효과가 있다고 알려져 있다. 본 연구에서 는 스피룰리나 정제수 추출물의 UVB로 유도된 활성산소종 ROS (reactive oxygen species) 소거능과 항산 화능을 확인하였다. 스피룰리나 정제수 추출물 0.05, 0.10, 0.50 1.0 mg/mL의 DPPH 라디칼 소거능, FRAP 환원능 및 ABTS+ 라디칼 소거능을 측정하여 항산화효과를 확인하였다. 대체실험동물모델인 Zebrafish를 이용하여 스피룰리나 정제수 추출물을 0.05, 0.10, 0.50 mg/mL 농도로 처리하여 응고율, 부 화율, 심장독성을 측정하였으며, 스피룰라나 추출물을 0.05, 0.10, 0.50 mg/mL 농도로 처리한 후, DCFH-DA로 염색하여 UVB로 유도된 ROS 저해효과를 확인하였다. 항산화효과 측정 결과 양성대조군인 ascorbic acid와 비교시 DPPH, Frpa, ABTS 모두 농도 의존적으로 항산화 효과가 있음을 확인하였다. 대체 실험동물인 Zebrafish를 이용하여 응고율과 부화율, 심박수를 측정한 결과 0.5 mg/mL을 제외한 0.05, 0.10 mg/mL에서는 대조군과 비교 시 독성이 없음을 확인 하였다. UVB로 유도된 Zebrafish의 ROS 소거 능은 양성대조군에 비해 높은 ROS 감소 효과를 나타내었다. 본 연구의 결과는 스피룰라나 정제수 추출물 이 자외선 및 피부 보호 화장품 소재로 사용가치가 있음을 시사한다.
        4,000원
        119.
        2020.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        As water resources are limited and legal regulations are strengthened, there is a growing need to reuse residuals in WTP(Water Treatment Plant). In this study, membrane filtration system was constructed and its operation method was studied for water quality stabilization and reuse of WTP residuals. The operation parameters were stable for 1 year and 6 months. Membrane fouling was identified as particulate pollution (activated carbon) and inorganic pollution (manganese). The membrane system was operated steadily with raw water of high concentration SS(Suspended solid) containing activated carbon because membrane fouling was reduced by the effect of End-Free type. In the case of inorganic contamination, dissolved manganese eluted by chemicals and acted as a membrane fouling source, and the operating conditions for minimizing membrane fouling were confirmed by newly developing application methods and types of cleaning chemicals. Based on the results, design parameters for reducing manganese membrane fouling were derived.
        4,300원
        120.
        2020.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Consumers want to express their original unique personality, and even are willing to endure high expenses in order to do this. One noticeable strategy in the market, used by companies to suit for this consumer sentiment, is that of employing limited edition marketing and limited free gifts. This study investigated the effects of limited free gifts on consumer response. Specifically, the present study examined how the need for uniqueness moderated the effects of limited free gifts on brand commitment and attitudes. The online survey method was used to gather the data and a total of 224 data were used to analyze data. The results of the research were as follows. The findings revealed four dimensions of limited free gifts: scarcity/specialty, not for sale, complementarity, and risk. Complementarity positively affected brand commitment, while all four dimensions of limited free gifts positively influenced brand attitude. In addition, the need for uniqueness was proven to be the strongest variable which positively influenced brand commitment and attitudes. Also, when the need for uniqueness was applied as a moderating variable, depending on the levels of the need for uniqueness, the effects of riskiness on the consumer’s response were shown to be different. The findings of this study infer various academic and practical applications.
        5,500원