• Title/Summary/Keyword: stable limits

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Experimental Study on the Flame Stable Region of Natural Gases from Various Producing Districts (산지별 천연가스의 화염 안정영역에 관한 실험적 연구)

  • Lee, Chang-Eon;Hong, Sung-Chang;Jeong, Young-Sik;You, Hyun-Seok;Lee, Seung-Jun;Her, Jae-Young;Hwang, Cheol-Hong
    • 한국연소학회:학술대회논문집
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    • 2007.05a
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    • pp.69-75
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    • 2007
  • In this study, the difference of flame stability zone for natural gases from producing districts was studied experimentally using a new type of flame stability diagram. The similarity of stable flame zone between a domestic appliance and an interchangeability test(IT) burner is also examined. As a result, the stable flame zones expressed by limits curves of flame lifting and yellow tipping show the similar results in a domestic gas range and IT burner. Furthermore, IT burner can reproduce the flash back phenomena and show the distinct difference of fuel type as the burner diameter is increased. To suggest the new type of flame stability diagram in the respect of fuel interchangeability, the air flowrate and Wobbe fuel flowrate were adopted as axis coordinates. It can be identified that the new diagram can provide the useful information on the difference of flame stability zone, heat input rate and air-fuel ratio when a fuel is altered to other fuels under the identical operating conditions. Finally, the stable flame zones for natural gas of 6 type are compared, and the detailed information to use as the interchangeability fuels of standard natural gas is provided using the new type of flame stability diagram.

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Analysis on Stable Grasping based on Three-dimensional Acceleration Convex Polytope for Multi-fingered Robot (3차원 Acceleration Convex Polytope를 기반으로 한 로봇 손의 안정한 파지 분석)

  • Jang, Myeong-Eon;Lee, Ji-Hong
    • Journal of Institute of Control, Robotics and Systems
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    • v.15 no.1
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    • pp.99-104
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    • 2009
  • This article describes the analysis of stable grasping for multi-fingered robot. An analysis method of stable grasping, which is based on the three-dimensional acceleration convex polytope, is proposed. This method is derived from combining dynamic equations governing object motion and robot motion, force relationship and acceleration relationship between robot fingers and object's gravity center through contact condition, and constraint equations for satisfying no-slip conditions at every contact points. After mapping no-slip condition to torque space, we derived intersected region of given torque bounds and the mapped region in torque space so that the intersected region in torque space guarantees no excessive torque as well as no-slip at the contact points. The intersected region in torque space is mapped to an acceleration convex polytope corresponding to the maximum acceleration boundaries which can be exerted by the robot fingers under the given individual bounds of each joints torque and without causing slip at the contacts. As will be shown through the analysis and examples, the stable grasping depends on the joint driving torque limits, the posture and the mass of robot fingers, the configuration and the mass of an object, the grasp position, the friction coefficients between the object surface and finger end-effectors.

Characterization of Atomic Emission Detector for Gas Chromatography Using Cylindrical Microwave Cavity (원통형 Microwave Cavity를 이용한 기체크로마토그라프 원자발광 검출기의 특성에 관한 연구)

  • Park, Young-Joo;Yoo, Hee-Soo
    • Analytical Science and Technology
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    • v.5 no.3
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    • pp.263-268
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    • 1992
  • A plasma source with cylindrical microwave cavity was used as atomic emission detector for gas chromatography. Detection limits of several elements were determined for this system. Detection limits for bromine and sulfur were 0.46 pg/s and 0.51 ng/s, respectively. The plasma was stable at the range of flow rate of 10 to 20mL/min.

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Supersonic Combustion Studies for SCRamjet Engines

  • Driscoll, James F.
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2004.03a
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    • pp.1-14
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    • 2004
  • Experiments were performed in order to examine the stability of hydrocarbon-fueled flames in cavity flameholders in supersonic airflows. Methane and ethylene were burned in two different cavity configurations having aft walls ramped at 22.5 and 90$^{\circ}$. Air stagnation temperatures were 590 K at Mach 2 and 640 K at Mach 3. Lean blowout limits showed dependence on the air mass flowrates. Visual observations, planar laser induced fluorescence (PLIF) of nitric oxide (NO), and Schlieren imaging were used to investigate these phenomena. Large differences were noted between cavity floor and cavity ramp injection schemes. Cavity ramp injection provided better performance in most cases. Ethylene pilots have a wider range of stable operation than methane. Fuel flowrates at ignition showed similar trends as lean blowout limits, but higher flowrates were required.

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중국공산당의 정치개혁은 퇴보하는가: 시진핑 시기 당내 민주의 변화와 지속성

  • Lee, Dong-Gyu
    • 중국학논총
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    • no.65
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    • pp.215-234
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    • 2020
  • This paper aims to analyze the recent consolidation of Xi Jinping's power in the context of political reform of the Chinese Communist Party (CCP), and reason out its implications. After Reform and Opening Up, the CCP needed to adapt to the changing society, secure its legitimacy and reinforce its ruling power. Therefore, the CCP has practiced political reform focused on intra-democracy since 16th Party Congress in 2002. Intra-democracy in the CCP's collective leadership consists of two parts: a stable power succession, based on term limits and age limits, and a democratic management system, based on checks and compromises between political factions. Those mechanisms of intra-democracy are still functioning in the Xi Jinping era, which explains that the consolidation of Xi's power is the result of the agreement in the CCP. In other words, it is a short-term change to efficiently deal with challenges the CCP is facing.

Determination of Microquantities of Nicotine (니코틴의 미량 정량법)

  • 김찬호;김신일
    • Journal of the Korean Society of Tobacco Science
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    • v.3 no.2
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    • pp.77-81
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    • 1981
  • A flew spectroscopic method was developed to determine microquantities of nicotine with cyanogen chloride and pyrazolon. Absorption maximum of tile derivative solution appeared at 520nm. The color formed in the proposed method was stable for at least 30 min. at pH 7.5, and followed the Lambert-Beer's law between tile limits of 1 and 5 micrograms of nicotine. The relative errors in burley and flue-cured tobacco leaves were $\pm5%$ in comparison with the Griffith method.

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STIMULATING NEURAL ELECTRODE-A STUDY ON CHARGE INJECTION PROPERTIES OF IRIDIUM OXIDE FILMS

  • Lee, In-Seop;Ray A. Buchanan;Jim M.Williams
    • Journal of the Korean Vacuum Society
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    • v.4 no.S2
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    • pp.156-162
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    • 1995
  • For a stimulating neural electrode, the charge density should be as large as possible to provide adequate stimulation of the nervous system while allowing for miniaturization of the electrode. Since iridium oxide is able to produce high charge densities while preventing undesirable reactions due to charge storage, it has become a promising material for neural prostheses. Successful production of stable Ir and Ir oxide films on various substrates now limits the use of this material. Ir was deposited on two differently prepared surface of (mirror finish, passivation) surgical Ti-6AI-4V with several methods. Ion beam mixing of sputter deposited Ir films on passivated Ti-6AI-4V produced stable and good adherent Ir films. It was found that the increase in charge density of pure Ir on continuous cyclingis due to the accumulation of the oxide phase ( associated with a large surface area) in which the valence state of iridium changes and the double-layer capacitance increases. This study also showed that the double layer capacitance is equally or even more responsible for the high charge density of anodically formed Ir oxide.

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Robust Control Chart using Bootstrap Method (붓스트랩 방법을 이용한 로버스트 관리도)

  • 송서일;조영찬;박현규
    • Journal of Korean Society of Industrial and Systems Engineering
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    • v.26 no.3
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    • pp.39-49
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    • 2003
  • Statistical process cintrol is intended to assist operators of a stable system in monitoring whether a change has occurred in the process, and it uses several control charts as main tools. In design and use of control chart, it is rational that probability of false alarm is minimized in stable process and probability of detecting shifts is maximized in out-of-control. In this study, we establish bootstrap control limits for robust M-estimator chart by applying the bootstrap method, called resampling, which could not demand assumptions about pre-distribution when the process is skewed and/or the normality assumption is doubt. The results obtained in this study are summarized as follows : bootstrap M-estimator control chart is developed for applying bootstrap method to M-estimator chart, which is more robust to keep ARL when process contain contaminate quality characteristic.

Glucose Diffusion Limiting Membrane Based on Polyethyleneimine (PEI) Hydrogel for the Stabilization of Glucose Sensor

  • Kim, Suk-Joon;Shin, Woonsup
    • Journal of Electrochemical Science and Technology
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    • v.12 no.2
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    • pp.225-229
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    • 2021
  • Commercially available continuous glucose sensors require the operation stability for more than two weeks. Typically, the sensor comprises a sensing layer and an over-coating layer for the stable operation inside the body. In the sensing layer, enzymes and mediators are cross-linked together for the effective sensing of the glucose. The over-coating layer limits the flux of glucose and works as a biocompatible layer to the body fluids. Here, we report the simple preparation of the flux-limiting layer by the condensation of polyethyleneimine (PEI), tri-epoxide linker, and trimethylolpropane triglycidyl ether (PTGE). The sensor is constructed by a layer-by-layer drop-coating of the sensing layer containing glucose dehydrogenase and the PEI-derived blocking layer. It is stable for more than 14 days, which is enough for the sensor in the continuous monitor glucose monitoring (CGM) system.