• Title/Summary/Keyword: 액체금속

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Stretchable Current Collector Composing of DMSO-dopped Nano PEDOT:PSS Fibers for Stretchable Li-ion Batteries (신축성 리튬이온전지를 위한 DMSO 도핑 PEDOT:PSS 나노 섬유 집전체)

  • Kwon, O. Hyeon;Lee, Ji Hye;Kim, Jae-Kwang
    • Journal of the Korean Electrochemical Society
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    • v.24 no.4
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    • pp.93-99
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    • 2021
  • In order to decrease the weight of stretchable energy storage devices, interest in developing lightweight materials to replace metal current collectors is increasing. In this study, nanofibers prepared by electrospinning a conductive polymer, PEDOT:PSS, were used as current collectors for lithium ion batteries. The nanofiber showed improved electrical conductivity by using DMSO, a dopant, and indicated a stretch rate of 30% or more from the elasticity evaluation result. In addition, the use of the nanofiber current collector facilitates penetration of the liquid electrolyte and exhibits the effect of increasing the electronic conductivity through the nanofiber network. The lithium-ion battery using the DMSO-doped PEDOT:PSS@PAM nanofiber current collector indicated a high discharge capacity of 135mAh g-1, and indicated a high capacity retention rate of 73.5% after 1000 cycles. Thus, the excellent electrochemical stability and mechanical properties of conductive nanofibers showed that they can be used as lightweight current collectors for stretchable energy storage devices.

Study on High Sensitivity Metal Oxide Nanoparticle Sensors for HNS Monitoring of Emissions from Marine Industrial Facilities (해양산업시설 배출 HNS 모니터링을 위한 고감도 금속산화물 나노입자 센서에 대한 연구)

  • Changhan Lee;Sangsu An;Yuna Heo;Youngji Cho;Jiho Chang;Sangtae Lee;Sangwoo Oh;Moonjin Lee
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.28 no.spc
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    • pp.30-36
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    • 2022
  • A sensor is needed to continuously and automatically measure the change in HNS concentration in industrial facilities that directly discharge to the sea after water treatment. The basic function of the sensor is to be able to detect ppb levels even at room temperature. Therefore, a method for increasing the sensitivity of the existing sensor is proposed. First, a method for increasing the conductivity of a film using a conductive carbon-based additive in a nanoparticle thin film and a method for increasing ion adsorption on the surface using a catalyst metal were studied.. To improve conductivity, carbon black was selected as an additive in the film using ITO nanoparticles, and the performance change of the sensor according to the content of the additive was observed. As a result, the change in resistance and response time due to the increase in conductivity at a CB content of 5 wt% could be observed, and notably, the lower limit of detection was lowered to about 250 ppb in an experiment with organic solvents. In addition, to increase the degree of ion adsorption in the liquid, an experiment was conducted using a sample in which a surface catalyst layer was formed by sputtering Au. Notably, the response of the sensor increased by more than 20% and the average lower limit of detection was lowered to 61 ppm. This result confirmed that the chemical resistance sensor using metal oxide nanoparticles could detect HNS of several tens of ppb even at room temperature.

Characteristics of Rahnella aquatilis Strain AY2000 for an Anti-Yeast Substance Production (항효모성 물질 생산을 위한 Rahnella aquatilis AY2000 균주의 생육특성)

  • Kang, Min-Jung;Lee, Bok-Kyu;Kim, Kwang-Hyeon
    • Microbiology and Biotechnology Letters
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    • v.36 no.3
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    • pp.215-220
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    • 2008
  • Rahnella aquatilis AY2000 has an unique characteristic which produces an anti-yeast substance (AYS). The AYS of the strain AY2000 was always secreted on agar plate, however, its activity in liquid culture was labile upon storage of the medium. In this paper, cultural conditions of the strain AY2000 for the AYS production were investigated in liquid culture, and minimal inhibitory concentration (MIC) against Saccharomyces cerevisiae was determined for the AYS activity. MIC of the AYS cultured in PYG broth at $^25{\circ}C$ for 24 hr was $23.5{\mu}g/mL$, however, that in MYCS (pH 5.5) broth at the same condition was $15.5{\mu}g/mL$. The activity of the AYS had increased rather in MYCS broth excluded $NH_4$-citrate than in the same broth contained $NH_4$-citrate, and MIC of the AYS produced in MYCS broth without $NH_4$-citrate was $15.5{\mu}g/mL$. When the strain AY2000 was maintained in MYCS broth without $NH_4$-citrate but added $100{\mu}M$ $FeCl_3$, the activity of the AYS had increased and its MIC was $7.8{\mu}g/mL$. MIC of the AYS was $7.8{\mu}g/mL$ after the strain AY2000 was cultured in MYCS broth containing $100{\mu}M$ $FeCl_3$ without $NH_4$-citrate, however, its MIC was $31.3{\mu}g/mL$ after 48-60 hr culture in the same broth.

Decomposition of Eco-friendly Liquid Propellants over Ruthenium/Al2O3/metal foam Catalysts (Ru/Al2O3/메탈폼 촉매를 이용한 친환경 액체추진제 분해)

  • Yoo, Dalsan;Jeon, Jong-Ki
    • Clean Technology
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    • v.25 no.3
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    • pp.256-262
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    • 2019
  • Hydroxylammonium nitrate (HAN)-based liquid propellants are attracting attention as environmentally friendly propellants because they are not carcinogens and the combustion gases have little toxicity. The catalyst used to decompose the HAN-based liquid propellant in a thruster must have both low temperature activity and high heat resistance. The objective of this study is to prepare an Ru/alumina/metal foam catalyst by supporting alumina slurry on the surface of NiCrAl metal foam using a washing coating method and then to support a ruthenium precursor thereon. The decomposition activity of a HAN aqueous solution of the Ru/alumina/metal foam catalyst was evaluated. The effect of the number of repetitive coatings of alumina slurry on the physical properties of the alumina/metal foam was analyzed. As the number of alumina wash coatings increased, mesopores with a diameter of about 7 nm were well-developed, thereby increasing the surface area and pore volume. It was optimal to repeat the wash coating alumina on the metal foam 12 times to maximize the surface area and pore volume of the alumina/metal foam. Mesopores were also well developed on the surface of the Ru/alumina/metal foam catalyst. It was found that the metal form itself without the active metal and alumina can promote the decomposition reaction of the HAN aqueous solution. In the case of the Ru/alumina/metal foam-550 catalyst, the decomposition onset temperature was significantly lowered compared with that of the thermal decomposition reaction, and ${\Delta}P$ could be greatly increased in the decomposition of the HAN aqueous solution. However, when the catalyst was calcined at $1,200^{\circ}C$, the catalytic activity was lowered inevitably because the surface area and pore volume of the catalyst were drastically reduced and Ru was sintered. Further research is needed to improve the heat resistance of Ru/alumina/metal foam catalysts.

RFID Based Mobile Robot Docking Using Estimated DOA (방향 측정 RFID를 이용한 로봇 이동 시스템)

  • Kim, Myungsik;Kim, Kwangsoo
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.37C no.9
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    • pp.802-810
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    • 2012
  • This paper describes RFID(Radio Frequency Identification) based target acquisition and docking system. RFID is non-contact identification system, which can send relatively large amount of information using RF signal. Robot employing RFID reader can identify neighboring tag attached objects without any other sensing or supporting systems such as vision sensor. However, the current RFID does not provide spatial information of the identified object, the target docking problem remains in order to execute a task in a real environment. For the problem, the direction sensing RFID reader is developed using a dual-directional antenna. The dual-directional antenna is an antenna set, which is composed of perpendicularly positioned two identical directional antennas. By comparing the received signal strength in each antenna, the robot can know the DOA (Direction of Arrival) of transmitted RF signal. In practice, the DOA estimation poses a significant technical challenge, since the RF signal is easily distorted by the surrounded environmental conditions. Therefore, the robot loses its way to the target in an electromagnetically disturbed environment. For the problem, the g-filter based error correction algorithm is developed in this paper. The algorithm reduces the error using the difference of variances between current estimated and the previously filtered directions. The simulation and experiment results clearly demonstrate that the robot equipped with the developed system can successfully dock to a target tag in obstacles-cluttered environment.

Electrochemical Characteristics of $V_2O_5$ based All Solid State Thin Film Microbattery by Ex-situ Sputtering Method (Ex-situ 스퍼터링법에 의한 $V_2O_5$ 전 고상 박막전지의 전기화학적 특성)

  • Lim Y.C.;Nam S.C.;Jeon E.J.;Yoon Y.S.;Cho W.I.;Cho B.W.;Chun H.S.;Yun K.S.
    • Journal of the Korean Electrochemical Society
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    • v.3 no.1
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    • pp.44-48
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    • 2000
  • Amorphous $V_2O_5$ cathode thin films were prepared by DC-magnetron sputtering at room temperature and the thin film rechargeable lithium batteries were fabricated with the configuration of $V_2O_5/LIPON/Li$ using sequential ex-situ thin film deposition techniques. The electrochemical characteristics of $V_2O_5$ cathode materials Prepared at 80/20 of $Ar/O_2$ ratio showed high capacity and cycling behaviors by half cell test. LIPON solid electrolytes films were prepared by RF-magnetron sputtering using the self-made $Li_3PO_4$ target in pure $N_2$ atmosphere, and it was very stable for lithium contact in the range of 1.2-4.0 V vs. Li. Metallic lithium were deposited on LIPON electrolyte by thermal evaporation methode in dry room. Vanadium oxide based full cell system showed the initial discharge capacity of $150{\mu}A/cm^2{\mu}m$ in the range of $1.2\~3.5V$.

Multi-layered Gap Measurement on In-Vessel Cerium Retention Using Ultrasonic Wave Reflective Pattern Analysis and Frequency Diversity Signal Processing (초음파 반사 패턴과 주파수 대역 분할 신호처리를 이용한 다층구조인 노내 간극 측정)

  • Koo, Kil-Mo;Sim, Cheul-Mu;Kim, Jong-Hwan;Kim, Sang-Baik;Kim, Hee-Dong;Park, Chi-Seung
    • Journal of the Korean Society for Nondestructive Testing
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    • v.20 no.4
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    • pp.314-321
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    • 2000
  • A gap between a $Al_2O_3/Fe$ thermite and lower head vessel is formed in the lower-plenum arrested vessel attack(LAVA) experiment which is the 1st phase study of simulation of naturally arrested vessel attack in vessel(SONATA-IV). The gap measurement using a conventional ultrasonic method would be lack of a reliability due to the structure complexity and the metallurgical grain size change of the lower head HAZ occurred by a thermite $Al_2O_3/Fe$ melt or a $Al_2O_3$ melt at $2300^{\circ}C$. The grain echoes having false signals and lower S/N ratio signals are detected due to a multiple scattering, a mode conversion and an attenuation of a ultrasonic resulted from at the interface of increased grain size zone. In this test, the signals pattern was classified to understand the behavior of the ultrasonic in a multi-layer specimen of solid-liquid-solid of assuming that the thermite and the lower head vessel is immersed. The polarity threshold algorithm of frequency diversity gives us the enhancement about 6dB of the ratio S/N.

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Studies on the cellulase properties of Aspergillus clavatus from the Cellulose-Cultural Properties (섬유질 문화재로부터 분리된 Aspergillus clavatus의 섬유소분해호소에 관한 연구)

  • Chung, Hee-Jin;Han, Sung-Hee;Ahn, Hee-Kyun;Min, Kyung-Hee
    • The Korean Journal of Mycology
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    • v.15 no.1
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    • pp.29-37
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    • 1987
  • Cellulolytic mocrooganisms were isolated from the cellulose-cultural properties. Among them, Aspergillus clavatus with the highest cellulase activity was identified by the morphological characteristics and it's enzyme activities were compared on the various cultural conditions. It was found that the induction of carboxymethylcellulase(CMCase), avicelase and salicinase in CMC liquid media showed the highest enzyme acitivity on five day's cultivation at $30^{\circ}C$ and thereafter their activities were gradually decreased with time. After crude extracellular enzymes precipitated with the 70% saturated ammonium sulfate solution were dialyzed with 20 mM acetate buffer pH 6.0, each crude enzyme was examined. The optimal activities of CMCase and avicelase were both found to be at $50^{\circ}C$ and pH 6.0. Their thermal stability was appeared at the $50^{\circ}C$. CMCase and avicelase had the maxima activities with 1.5% and 2.2% substrate concentration, respectively. The concentration of 5 mM $Mg^{++}$ or $Ca^{++}$ was found to have a maximum cellulase activity and its activity was inhibited with more than 5 mM $Cu^{++}$ and $Zn^{++}$ concentration. Cellulase activity was also inhibited sensitively by the inhibitors such as 2-mercaptoethanol, iodine and sodium azide.

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Recovery of Silicon from Silicon Sludge by Electrolysis (실리콘 슬러지로부터 실리콘의 전해회수(電解回收))

  • Park, Jesik;Jang, Hee Dong;Lee, Churl Kyoung
    • Resources Recycling
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    • v.21 no.5
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    • pp.31-37
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    • 2012
  • As a recovery of elemental silicon from the sludge of Si wafer process, a process of mechanical separation-chlorine roasting-electrolysis has been suggested. The silicon sludge consisted of Si, SiC, machine oil, and metallic impurities. The oil and metal impurities was removed by mechanical separation. The Si-SiC mixture was converted to silicon chloride by chlorine roasting at $1000^{\circ}C$ for 1 hr and the silicon chloride was dissolved into an ionic liquid of $[Bmpy]Tf_2N$ as an electrolyte. Cyclic voltammetry results showed an wide voltage window of pure $[Bmpy]Tf_2N$ and a reduction peak of elemental Si from $[Bmpy]Tf_2N$ dissolved $SiCl_4$ on Au electrode, respectively. The silicon deposits could be prepared on the Au electrode by the potentiostatic electrolysis of -1.9 V vs. Pt-QRE. The elemental silicon uniformly electrodeposited was confirmed by various analytical techniques including XRD, FE-SEM with EDS, and XPS. Any impurity was not detected except trace oxygen contaminated during handling for analysis.

Fabrication of $MgB_2$ Sheet by Powder Rolling Method (분말압연 공정에 의한 $MgB_2$ 판재 제조)

  • Chung, K.C.;Jeong, T.J.;Kim, T.H.;Ahn, S.T.;Park, Y.S.;Kim, D.H.;Wang, X.L.;Dou, S.X.
    • Progress in Superconductivity
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    • v.12 no.2
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    • pp.88-92
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    • 2011
  • [ $MgB_2$ ]superconducting sheets have been fabricated using powder roll compaction method. Sheet-type $MgB_2$ bulk samples were successfully fabricated using the pre-reacted $MgB_2$ powders. In this work, $MgB_2$ powders were compacted by two rotating rolls and squeezed out as a form of $MgB_2$ sheets of ~1 mm thickness. The rolling speed of 0.3-0.7 rpm and the gap distance of 0.3-0.8 mm between the two rollers were carefully controlled to get a full compaction of the powders into bulk $MgB_2$ sheets. The densities of $MgB_2$ sheets were 1.98-2.05 g/$cm^3$, which is 75.44-77.99 % of the theoretical value of 2.63 g/$cm^3$. And the density comparison was made compared to those of typical $MgB_2$ bulks from uni-axial pressing and $MgB_2$ wires from Powder-In-Tube processing.