• Title/Summary/Keyword: Poor stability

Search Result 525, Processing Time 0.048 seconds

A Bilateral Control for Telemanipulators with High Reduction Ratio Joints (고감속비의 관절을 가지는 원격조작기의 양방향 제어)

  • 안성호;윤지섭;이상정
    • Proceedings of the IEEK Conference
    • /
    • 2000.06e
    • /
    • pp.35-38
    • /
    • 2000
  • Since the telemanipulator consisting of high reduction ratio gear joints has a slow dynamics comparing with the master manipulator, its control signal is likely to be saturated resulting in poor tracking performance and deteriorated stability. This paper proposes a bilateral control scheme of a telemanipulator having high reduction ratio, which can compensate the control input saturation. The experimental results show that the proposed control scheme has excellent performances.

  • PDF

Electrical Conductivity of Polypyrrole/Copolyester Composite Films. 2. Composite Films Prepared from Copolyester-$FeCl_3$ Surface Absorption

  • Lee, Seong-Mo;Baik, Doo-Hyun
    • Proceedings of the Korean Fiber Society Conference
    • /
    • 1998.10a
    • /
    • pp.53-56
    • /
    • 1998
  • Polypyrrole (PPy) is regarded as one of the most Promising intrinsically or naturally conductive polymer for practical applications due to its relatively high electrical conductivity, environmental stability and low toxicity. The typical PPy, which is insoluble and infusible, exhibits poor processability and lacks essential mechanical properties. A number of papers have concerned the efforts to overcome these drawbacks. (omitted)

  • PDF

The effect of shielding gases on Inconel 625 GMA weldability (Inconel 625 GMA 용접성에 미치는 보호가스의 영향)

  • Kim, Yeong-Il;Ju, Jeong-Gwon;An, Jae-Ung;Choe, Jun-Tae
    • Proceedings of the KWS Conference
    • /
    • 2005.06a
    • /
    • pp.217-219
    • /
    • 2005
  • In the conventional GMAW of 9% Ni steel, Inconel wire has been employed. The major problem of the Inconel GMAW is that arc stability and fluidity of weld pool is poor. Lack of fusion and convex weld bead is liable to occur in case of 9% Ni steel because of low melting point of Inconel wire. In this study the effect of shielding gases on the Inconel 625 GMA weldability was investigated.

  • PDF

A New Substituent Constant $σ^{c+}4_s$;a Fit for π-Participation in Modified Hammett-Brown Equation

  • 조정호;신정휴
    • Bulletin of the Korean Chemical Society
    • /
    • v.17 no.4
    • /
    • pp.347-348
    • /
    • 1996
  • A set of substituent constants, σc+, has been widely used comparing the stability of carbocation in super acid condition. Plotting of 13C chemical shifts of cationic carbon (Δδc+) against σc+ constants yields an excellent correlation with a good correlation coefficient (r=0.999) for a cyclopentyl cation system. But these σc+ constants show poor linearity in norbornenyl cations that well known to show homoallylic stabilization in a cationic condition. We calculated the new substituent constant, σc+π, and found that the new substituent constants give an excellent correlation in π- and πσ-participating cation systems.

The Application of Disperse Dyes to the Ultra Low Liquor Ratio Dyeing System (초저욕비 염색을 위한 분산염료의 적용연구)

  • Kim, Tae-Gyeong;Kim, Jin-Su;Park, Hui-Mun;Nam, Chang-U
    • Proceedings of the Korean Society of Dyers and Finishers Conference
    • /
    • 2008.04a
    • /
    • pp.192-194
    • /
    • 2008
  • The study has focused on the dyeing properties of 4 kinds of high temperature type mono azo disperse dyes, widely used in the dyeing factory, under the ultra low liqour ratio (1:4) dyeing condition. Among those, C.I. Disperse Red 343 and C.I. Disperse Blue 79 showed un-levelled dyeing results from the ultra low liquor ratio dyeing bath as well as poor dispersion stability under the high temperature. We recommended some leveling agents to improve the leveling behavior of these dyes mentioned above. The milling technology should be further developed to achieve the dispersion stability.

  • PDF

Constrained MPC for uncertain time-delayed systems

  • Jeong, Seung-Cheol;Park, Poo-Gyeon
    • 제어로봇시스템학회:학술대회논문집
    • /
    • 2003.10a
    • /
    • pp.1905-1910
    • /
    • 2003
  • It is well known that parameter uncertainties and time-delays cannot be avoided in practice and result in poor performance and even instability. Nevertheless, to the authors' best knowledge, there exist few results on model predictive control (MPC) handling explicitly uncertain time-delayed systems. In this paper, we present an MPC algorithm for uncertain time-varying systems with input constraints and state-delay. An optimization problem is suggested to find a memoryless state-feedback MPC law and the closed-loop stability is established under feasibility and certain conditions.

  • PDF

The Enhanced Physico-Chemical and Electrochemical Properties for Surface Modified NiO Cathode for Molten Carbonate Fuel Cells (MCFCs)

  • Choi, Hee Seon;Kim, Keon;Yi, Cheol-Woo
    • Bulletin of the Korean Chemical Society
    • /
    • v.35 no.5
    • /
    • pp.1305-1311
    • /
    • 2014
  • The nickel oxide, the most widely used cathode material for the molten carbonate fuel cell (MCFC), has several disadvantages including NiO dissolution, poor mechanical strength, and corrosion phenomena during MCFC operation. The surface modification of NiO with lanthanum maintains the advantages, such as performance and stability, and suppresses the disadvantages of NiO cathode because the modification results in the formation of $LaNiO_3$ phase which has high conductivity, stability, and catalytic activity. As a result, La-modified NiO cathode shows low NiO dissolution, high degree of lithiation, and mechanical strength, and high cell performance and catalytic activity in comparison with the pristine NiO. These enhanced physico-chemical and electrochemical properties and the durability in marine environment allow MCFC to marine application as a auxiliary propulsion system.

LQ-servo design to command following and output-disturbance rejection (명령추종과 출력측 외란제거를 위한 LQ-servo 설계)

  • Yun, Seong-O;Suh, Byung-Suhl
    • Journal of Institute of Control, Robotics and Systems
    • /
    • v.3 no.5
    • /
    • pp.443-449
    • /
    • 1997
  • LQ-servo design procedure introduced by Athans is a method using a partial states feedback and an output feedback in order to improve the poor performance robustness of the LQR as well as to maintain its stability robustness. Although the method guarantees good stability robustness, it is not effective in performance robustness as it does not match the singular value at low or high frequencies of the transfer matrix obtained by breaking at the plant output. This paper intends propose of a new method, using the limited behaviour of the control gain introduced by Kwakernaak and Sivan, in order to improve it does it refer to controlga introduced by kwakernaak or the new metho Anblguouls.

  • PDF

Systemic Availability and Pharmacokinetics of Surfactin, a Lipopeptide Produced by Bacillus subtilis BC1212 in Rats

  • Lim Jong-Hwan;Kim Myoung-Seok;Park Byung-Kwon;Hwang Youn-Hwan;Hwang Mi-Hyun;Park Seung-Chun;Yun Hyo-In
    • Toxicological Research
    • /
    • v.21 no.4
    • /
    • pp.319-323
    • /
    • 2005
  • The aim of the present study was to evaluate systemic bioavailability of surfactin and to determine its pharmacokinetic profiles. The stability of surfactin to pH, temperature and protease was evaluated. Surfactin was resistant to high temperature, a wide range of pH and the action of hydrolytic enzymes. The pharmacokinetic natures of surfactin which were shown the short half-life, rapid clearance and poor bioavailability. The results of study should provide preliminary data of surfactin for further dose-finding studies and for the design of application forms. It is also be important to a context of the safety of surfactin.

Study of Dyeing Properties by Swelling Agent on meta-aramid Fiber with Cationic Dyes (Swelling agent에 따른 메타계 아라미드 섬유의 Cationic dye 염색특성)

  • Kim, Eun-Mi;Park, Chung-Won;Choi, Jae-Hong
    • Textile Coloration and Finishing
    • /
    • v.24 no.1
    • /
    • pp.1-7
    • /
    • 2012
  • Dyeing and fastness characteristics of 100% meta-aramid fiber were investigated with cationic dyes and swelling agents under various dyeing conditions such as dyeing temperature and pH of dye bath. Dye exhaustion started at around $80^{\circ}C$ and settled down at $130^{\circ}C$. Among swelling agents used, N-methyl formanilide showed comparatively higher K/S values comparing to 1-phenoxypropan-2-ol. Under weak acidic conditions in the range pH 5 to 7, the exhaustion of cationic dyes could be enhanced leading to higher adsorption and stability of colorimetric property. Wash and rubbing fastness were generally good but low light fastness found can be attributable to the poor photo-stability of the cationic dyes.