• Title, Summary, Keyword: Super stability

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Manufacture of Lapping Wheel for Electrolytic Dressing and Evaluation of Electrolytic Characteristics (연속 전해드레싱용 래핑지석의 제작 및 전해 특성 평가)

  • 최재영;이은상;송지복
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.914-917
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    • 2000
  • Application of ceramics, carbide, ferrite has grown considerably due to significant improvement in their mechanical properties such as light weight, chemical stability , super wear resistance and electronical. Despite these character, the me of advanced material has not increased because of poor machinability. The method of using of metal bond wheel was proposed. But it is difficult that metal bond wheel can be dressed. Recently, the technology of in-process electrolytic dressing is developed to solve this problem. This method need wheel for electrolytic dressing, power supply and electrolyte. But development of wheel for electrolytic dressing is the most need. The aim of this study is development of wheel for electrolytic and appraisement of CIB-diamond lapping wheel

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A Study on the Development of In-Processor Dressing Lapping Wheel and its Evaluation of Machining Characteristics (연속 전해드레싱용 래핑숫돌 개발 및 성능평가)

  • Choe, Jae-Yeong;Lee, Eun-Sang;Song, Ji-Bok
    • Journal of the Korean Society for Precision Engineering
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    • v.18 no.11
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    • pp.132-137
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    • 2001
  • Application of ceramics, carbide, ferrite has grown considerably due to their mechanical properties such as high degree hardness, chemical stability, super wear resistance. Despite these characters, the use of advanced material has not increased because of poor machinability. The application of metal bonded wheel was proposed. But it is difficult that metal bond wheel can be dressed. Recently, to solve this problem, the technology of in-process electrolytic dressing is developed. This method need wheel for electrolytic dressing, power supply and electrolyte. The aim of this study is development of CIB-D wheel for electrolytic and its evaluation of electrolytic characteristics, and achieve ultra-precision lapping of carbide, optic glass.

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Review: Development of Numencal Wave Flume CABMAS-SURF (SUper Roiler Flume for Computer Aided Design of MAritime Structure)

  • Fujima, Koji
    • Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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    • pp.1-13
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    • 2002
  • For design of maritime structure, it is necessary to evaluate the effect and stability of the structure against wave action. Laboratory model experiments and their empirical formulas are mainly used to estimate those at present, although empirical formulas have a problem of accuracy and hydraulic experiments of cost and duration. In addition, performance-based design, which may be popularized as a new design concept in the near future, requires much more information than that obtained by empirical formulas and laboratory tests. Thus, numerical simulation may become more important hereafter for structure design. (omitted)

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SMES Modeling with Consideration of Operating Characteristics and Transient Stability Analysis (계통안정화용 SMES의 운전특성을 고려한 모델링과 과도안정도 해석)

  • Lee, Jong-Pil;Nam, Sang-Cheon;Lim, Jae-Yoon;Kim, Jung-Hoon
    • Proceedings of the KIEE Conference
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    • pp.1153-1155
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    • 1998
  • Super-conducting Magnetic Energy Storage(SMES) system is considered to be useful unit to power system stabilizer because of high efficiency and quick response. For effective operating of SMES, we need much studies on accurate modeling and interface characteristics of SMES. In this paper, we propose useful method to SMES, modeling using Artificial Neural Network. Interface technique of proposed model and criterion of stabilization effect is presented. In addition, to demonstrate the validity of proposed method. the simulations were carried out on 3-machine 9-bus system.

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Preparation and Electrochemical properties of LiMn2O4 cathode of Lithium ion battery for Electric vehicles

  • Jeong, In-Seong;Gu, Hal-Bon
    • Proceedings of the KIPE Conference
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    • pp.934-937
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    • 1998
  • Charge/discharge property of LiMn2O4 was investigated with LiMn2O4/Li cell for use of lithium ion battery in electric vehicle. LiMn2O4 calcined at $800^{\circ}C$ for 36hr show high charge/discharge capacity and excellent cycle stability than that of others. This is found to be in agreement with expectation in the X-ray diffraction analysis. In addition, the kind and volume of conductive agent involved in LiMn2O4 cathode is excellent at super-s-black and 20wt%, respectively.

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Dynamic Characteristics Analysis of a Rigid Rotor System Supported by Journal Air Bearings (저널 공기 베어링에 의해 지지되어진 강체 로터 계의 동특성 해석)

  • 권대규;곡순이;이성철
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.1026-1031
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    • 2001
  • In this paper. the dynamic characteristics of a super high-speed tilting-pad air bearing(TPGB) used in a turbo expander with high expansion ratio are analyzed. The dynamic behavior and stability of a rotary system supported by two journal air bearings are investigated numerically. The transient response of the shaft is obtained by simultaneously solving the equation of motion of the shaft and the dynamic Reynolds equation. The stiffness and damping coefficients of the bearing are calculated from the loading coefficients of the bearing are calculated from the loading capacity. shaft velocity and displacement by using a curve fitting method. The natural frequencies of the 1st and 2nd rigid modes can be calculated from these coefficients. The theoretical method of a rigid rotor system is verified by experimentsut.

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Electrode of Low Impedance by Polypyrrole Addition for Supercapacitor (폴리피롤 첨가에 의한 supercapacitor용 저 임피던스 전극)

  • 김경민;장인영;강안수
    • Proceedings of the Safety Management and Science Conference
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    • pp.343-350
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    • 2003
  • The best Ppy weight ratio was 7 wt% and the optimal electrode composition ratio was 78 : 17 : 5 wt.% of (MSP-20 : BP-20 =1 : 1), (Super P : Ppy =10 : 7) and P(VdF-co-HFP). Implantation of Ppy as the conducting agents have led to superior electrochemical characteristics because of the low of internal resistance and faradaic capacitance. The result of unit cell with Ppy 7 wt% were as follows: 28.02 Fig of specific capacitance, 1.34 Ω of DC-ESR and 0.36 Ω of AC-ESR. Unit cell showed a good stability up to 200 charge-discharge cycles, retaining 82% of their original capacity at 200 cycles. From the analysis of impedance, the electrodes with Ppy 7 wt% showed low ESR, low charge transfer resistance and quick reaction rate. It was inferred that quick charge-discharge was possible. As compared with the specific capacitance (rectangular shape) of CV, it was also concluded that the specific capacitance originated from thecompound phenomena of the faradaic capacitance by oxidation and reduction of Ppy and the non-faradaic capacitance by adsorption-desorption of activated carbon.

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Electrosynthesis and Electrochemical Properties of Metal Oxide Nano Wire/ P-type Conductive Polymer Composite Film

  • Siadat, S.O. Ranaei
    • Journal of Electrochemical Science and Technology
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    • v.6 no.3
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    • pp.81-87
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    • 2015
  • This study introduces a facile strategy to prepare metal oxide/conducting polymer nanocomposites that may have promising applications in energy storage devices. Ploy aniline/nano wire manganese dioxide (PANI/NwMnO2) was synthesized by cyclic voltammetry on glassy carbon electrode. Morphology and structure of the composite, pure PANI, MnO2 nanowires were fully characterized using XRD and SEM analysis. Electrochemical studies shows excellent synergistic effect between PANI and MnO2 nanowires which results in its capacitance increase and cycle stability against PANI electrode. Specific capacitances of PANI/NwMnO2 and PANI were 456 and 190 F/g respectively. The electrochemical performance of electrodes studied using cyclic voltammetry, Galvanostatic charge/discharge and impedance spectroscopy.

Analysis and hazard evaluation of heat-transfer fluids for the direct contact cooling system

  • Hong, Joo Hi;Lee, Yeonhee;Shin, Youhwan;Karng, Sarngwoo;Kim, Youngil;Kim, Seoyoung
    • Analytical Science and Technology
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    • v.19 no.4
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    • pp.323-332
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    • 2006
  • This paper discusses several low-temperature heat-tranfer fluids, including water-based inorganic salt, organic salt, alcohol/glycol mixtures, silicones, and halogenated hydrocarbons in order to choose the best heat-transfer fluid for the newly designed direct contact refrigeration system. So, it contains a survey on commercial products such as propylene glycol and potassium formate as newly used in super market and food processing refrigeration. The stability of commercial fluids at the working temperature of $-20^{\circ}C$ was monitored as a function of time up to two months. And organic and inorganic compositions of candidate fluids were obtained by analytical instruments such as ES, XRF, AAS, ICP-AES, GC, and GC-MS. Analysis results indicate that commercial propylene glycol is very efficient and safe heat transfer fluids for the direct cooling system with liquid phase.

Mechanical Properties and Microstructure of Aluminum Alloys with Dispersed Nanoscale Quasicrystalline Particles

  • Fujita, Masashi;Kimura, Hisamichi;Inoue, Akihisa
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • pp.708-709
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    • 2006
  • New Al-based alloys with very high ultimate tensile strength were developed in high Al concentration range of 91-95 at.% for Al-Fe-Cr-Ti-M (M: Co and Mo) systems and Al-Fe-Cr-Mo-Ti-Co system by the dispersion of nanoscale quasicrystalline particles in Al phase. The effect of adding elements, M was discussed in the viewpoint of stability of super-cooled liquid state and formation ability of quasicrystalline phase. The P/M Al-Fe-Cr-Ti-M alloys with dispersed nanoscale quasicrystalline particles exhibited ultimate tensile strength of 350MPa at 573K and 200MPa at 673K.

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