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        검색결과 10

        1.
        2024.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Cu2+/polyacrylonitrile composite fibers were prepared by electrospinning, and then Cu/carbon nanofibers (denoted as Cu/ CNF-X; X = Cu content, 0, 3, or 5 wt%) were formed by calcining them. The effects of Cu2+ content and carbonization temperature on the conductivity and electrothermal conversion of Cu/CNF-X were investigated. The results revealed that the conductivity and electrothermal properties of Cu/CNF-X improve with the increase in the Cu2+ content and carbonization temperature. When the carbonization temperature was 800, 900, or 1000 °C, the conductivity of Cu/CNF-5 (0.08, 0.68, or 2.48 S/cm, respectively) increased to 1.6, 1.5, or 1.6 times that of Cu/CNF-0, respectively. The highest instantaneous surface temperatures of Cu/CNF-5 calcined at 800, 900, and 1000 °C (36, 145, and 270.2 °C, respectively) increased by 4, 25.5, and 44.6 °C, respectively, compared with those of the corresponding Cu/CNF-0 samples (32, 120.3, and 225.6 °C, respectively). Thus, the addition of a small amount of Cu2+ effectively improved the conductivity and electrothermal conversion performance of Cu/CNF-X, which has potential application value in industrial products in the future.
        4,000원
        2.
        2023.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        As a promising anode for sodium-ion batteries (SIBs), cobalt sulfide ( CoS2) has attracted extensive attention due to its high theoretical capacity, easy preparation, and superior electrochemical activity. However, its intrinsic low conductivity and large volume expansion result in poor cycling ability. Herein, nitrogen-doped carbon-coated CoS2 nanoparticles (N–C@ CoS2) were prepared by a C3N4 soft-template-assisted method. Carbon coating improves the conductivity and prevents the aggregation of CoS2 nanoparticles. In addition, the C3N4 template provides a porous graphene-like structure as a conductive framework, affording a fast and constant transport path for electrons and void space for buffering the volume change of CoS2 nanoparticles. Benefitting from the superiorities, the Na-storage properties of the N–C@CoS2 electrode are remarkably boosted. The advanced anode delivers a long-term capacity of 376.27 mAh g− 1 at 0.1 A g− 1 after 500 cycles. This method can also apply to preparing other metal sulfide materials for SIBs and provides the relevant experimental basis for the further development of energy storage materials.
        4,000원
        3.
        2022.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Commercial carbon fiber cloth (CFC) is treated by the Joule-heating pyrolysis method in air to boost its capacitive performance on the premise of energy- and time-saving considerations. A thermoelectric coupling model suitable for the Jouleheating pyrolysis is successfully established based on the comparisons between the simulated temperatures and actually measured ones. The temperature field on CFC surface induced by the Joule heat presents a concentric-ellipse shape that the temperature in the core is the maximal and gradually decays outward. Increasing the direct current (DC) voltage which is applied to the CFC from 1.0 to 6.0 V, the core temperature on the CFC surface can be raised from 31 to 519 °C. The specific surface area and hydrophilicity of the as-prepared porous CFC are greatly improved compared with the pristine one. Electrochemical test shows that the optimal Joule-heating pyrolysis parameters falls at 5.0 V and 12.5 min, and the areal specific capacitance of as-obtained CFC-5.0-12.5 is about 80 folds that of the pristine CFC. In addition to the much shorter preparation time, all the characteristics including areal specific capacitance, rate performance, and electrical conductivity of the Joule-heating pyrolyzed CFC are superior to those of the electrical furnace pyrolyzed counterpart. The aqueous symmetrical supercapacitor made of CFC-5.0-12.5 electrodes exhibits considerable power and energy densities with respect to the previously reported carbon electrode-based supercapacitors. For conductive precursors, the Joule-heating pyrolysis can be an ideal substitute for the traditional electric furnace pyrolysis.
        4,300원
        4.
        2015.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Generally, there are many kinds of pumps used on a ship, which play an obbligato role to assist the ship’s running. However, due to the pump’s own motor, it becomes a main vibration resource that may cause serious problems in local. If the above situation happened, it may cause local resonance even structural damage. Also, the bigger the pump’s size is, the more serious the vibration is. Therefore, it is very important for researchers to estimate the vibrations situation of pumps accurately and avoid or reduce the probability of resonance. Based on a real marine pump-HHG8065, this paper did a vibration analysis by FEM (Finite Element Method) and compared the results with actual test. Finally, it gave a discussion on the estimation of pump and provided an improvement way to the vibration level.
        4,000원
        7.
        2004.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구는 동충하초속균의 자실체 인공 재배를 위한 기초자료를 얻고자 제주도 한라산에서 채집한 Cordyceps longissima, C. militaris, C. pruinosa 등 야생 동충하초의 형태적, 생리적 특성조사를 수행하였다. Cordyceps longissima : 지좌는 숙주에서 1~2개 발생하며 곤봉형 또는 불규칙형으로 표면이 다소 거칠고 적갈색을 띤다. 두부는 23~59×6~8 ㎜이며, 병부는 원통형으로 37~151×2.5~4.0 ㎜이다. 자낭각은 묻힌형으로 553~600×215~270 ㎛. 자낭은 가는 원통형으로 330~510×5~6 ㎛이며, 자낭포자는 11~13×1.4~1.8 ㎛이다. 자실체는 매미목 매미과의 곤충에서 발생하였다. 균사 생장은 MCM 배지에서 25℃, 4주 배양시 73 ㎜이며, 균사의 색택은 진황색을 나타내었다. 탄소원으로는 단당류인 glucose, 질소원으로는 potassium nitrate를 가장 잘 이용하였다. C. militaris : 지좌는 숙주에서 1~3개 발생하며 곤봉형으로 주황색을 띤다. 두부는 9~23×6~8㎜이며, 병부는 원통형으로 27~30×6~7 ㎜이다. 자낭각은 반묻힌형으로 465~510×260~310 ㎛. 자낭은 가는 원통형으로 320~385×4.2~4.8 ㎛이며, 자낭포자는 2.2~4.5×1.2~1.4 ㎛이다. 자실체는 나비목 곤충의 번데기에서 발생하였다. 균사 생장은 PDA 배지에서 25℃, 4주 배양시 71 ㎜이며, 균사의 색택은 연노랑색을 나타내었다. 탄소원으로는 단당류인 frucose, 질소원으로는 potassium nitrate를 가장 잘 이용하였다. C. pruinosa : 지좌는 숙주에서 1개 발생하며 곤봉형으로 주홍색을 띤다. 두부는 7~9×3~4이며, 병부는 원통형으로 13~22× 2~3 ㎜이다. 자낭각은 반묻힌형으로 350~520×130~310 ㎛. 자낭은 원통형으로 256~270×5~6㎛이며, 자낭포자는 3.2~5.1×0.8~1.3 ㎛이다. 자실체는 나비목 곤충의 번데기에서 발생하였다. 균사 생장은 PDA 배지에서 25℃, 4주 배양시 60 ㎜이며, 균사의 색택은 연붉은색을 나타내었다. 탄소원으로는 단당류인 arabinose와 mannose, 질소원으로는 sodium nitrite를 가장 잘 이용하였다.
        4,000원
        8.
        2016.10 서비스 종료(열람 제한)
        Background : Invitro antioxidant activity, polyphenol and flavonoid aglycone contents in black and green tea products of balloon flower leaves were investigated to provide valuable information for the further development and utilization of resources of Platycodon grandiflorum. Methods and Results : Flavonoid aglycone contents were investigated using HPLC (SHIMADZU, Japan) with a hypersil ODS column (125 mm × 4 mm, 5-μm particle, HP). DPPH and ABTS radical scavenging activities were measured by method of Lee & Lee (2004) with slight modification. Antioxidant activity, polyphenol and flavonoid contents in green tea were significantly higher than these in black tea. PC analysis indicated that first principal components explained 79.9% of the total variability for five traits investigated. PC2 explained 19.7% of the variation. Conclusion : It can be concluded from these results that these characteristics can reveal the active compound variation of black and green tea products of balloon flower leaves. These results provide scientific evidence for the utilization of balloon flower leaves.
        9.
        2015.12 KCI 등재 서비스 종료(열람 제한)
        The anti-diabetic effect of Cirsium setidens water extract and the combinations with Bletilla striata, Cymbidium kanran, and Sparganium stoloniferum Buch.-Ham. ethanolic extracts had been studied. The combination of four extracts (3:1:1:1) showed larger anti-diabetic activity in vitro and in vivo. It is notable that the single water extract from C. setidens exhibited more effective anti-diabetic effect than most of the combinations. We also investigated whether fermentation process was promoted the anti-diabetic activity. The data suggested the fermentation product of combination of four extracts (3:1:1:1) exhibited the strongest activity both in vitro and in vivo, which was higher than the non-fermented group. The result indicated the fermentation and the appropriate combination of extracts enhanced the anti-diabetes activity.
        10.
        2011.07 KCI 등재 서비스 종료(열람 제한)
        Objectives: This study is aimed at identifying the influential factors on the pulmonary function of ordinary residents in the surrounding areas of Yeosu Industrial Complex. Methods: The PFT (Pulmonary Function Test) was conducted on the target residents numbering 989 people (male 361, female 628). The exposed group (813 people) resided within the radius of 5km from Yeosu Industrial Complex and the control group (176 people) resided in the radius of more than 15 km from May 2007 to November 2007. The survey also took into account other factors including personal characteristics, life habits, respiratory diseases and allergic symptoms, medical histories, and the living environments of the residents in order to further identify influential factors on pulmonary function. Result: When comparing the PFT values of the exposure groups to the control group of the same city, values of the exposure groups were meaningfully lower with an %FEV1 of 107.05% and %FVC of 100.28%. Conversely, the control group reported an %FEV1 and %FVC of 107.26% and 102.85% respectively, indicating that ambient air pollutants reduce lung function. The odds ratio of asthma diagnosis history increased when a subjects residence was close to a heavily trafficked road, traffic amount was huge, a bed was used, and the family had less than four members. However the results were not statistically meaningful. The odds ratios of abnormal pulmonary function were statistically higher among those with asthma(OR=4.29, CI=1.75-10.56), wheezing (OR=2.59, CI=1.24-5.41), and nasal congestion (OR=2.87, CI=1.36-6.08) (p<0.01). The factors affecting FEV1 were symptoms including asthma, passive smoking and allergic eye disease (R2=0.049, p<0.001). For the FVC symptoms including asthma (R2=0.014, p<0.001) were measured. The analysis showed that FVC decreased with increases in O3 and CO(p<0.01). Furthermore, FEV1 decreased with increases in O3(p<0.01). Conclusions: These results will provide preliminary data for establishing responsive measures to protect the health of residents in industrial complexes from air pollution, and to develop lasting environmental health policies.