• Title, Summary, Keyword: ACM

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Non-isothermal TGA Study on Thermal Degradation Kinetics of ACM Rubber Composites (비등온 TGA를 이용한 ACM 고무복합재료의 열분해 거동 연구)

  • Ahn, WonSool;Lee, Hyung Seok
    • Elastomers and Composites
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    • v.48 no.2
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    • pp.161-166
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    • 2013
  • Thermal degradation behavior of chlorine cure-site ACM and carboxylic cure-site ACM rubbers was studied by non-isothermal TGA thermal analysis. Carboxylic cure-site ACM rubber exhibited comparatively more thermally stable than chlorine cure-site ACM, showing higher peak temperature, at which maximum reaction rate occurred. Activation energies from Kissinger method were calculated as 118.6 kJ/mol for the chlorine cure-site ACM and 105.5 kJ/mol for the carboxylic cure-site ACM, showing similar values from Flynn-Wall-Ozawa analysis over the conversion range of 0.1~0.2. From the analysis of the reaction order change, both samples seemed thermally decomposed through the multiple reaction mechanism as is the common rubber materials.

A Study on Physical Properties and Life Time Prediction of ACM Rubber for Automotive Engine Gasket (자동차 엔진 개스킷용 아크릴 고무의 물리적 특성과 수명 예측에 관한 연구)

  • Lee, Hyung-Seok;Do, Jong-Hwan;Ahn, Won-Sool;Kim, Cheol
    • Elastomers and Composites
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    • v.47 no.3
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    • pp.254-258
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    • 2012
  • Material characteristics and the prediction of life time of polyacrylic rubber (ACM) for automotive engine gasket were studied. Two kinds of ACM rubber compounds, having chlorine cure-site and carboxyl cure-site, were made with optimum formulations and the properties of each materials were examined. As a test results for the thermal properties and compression set, which are very important in the application for the automotive engine gasket, the compound using ACM with carboxyl cure-site was evaluated as having a better characteristics than that of ACM with chlorine cure-site. Arrhenius relationship based on time-temperature superposition principle (TTSP) was obtained through the accelerated heat aging test to predict the useful life-time for the compound using ACM with carboxyl cure-site.

Design of Active Control Engine Mount Using Direct Drive Electrodynamic Actuator (전동식 직접 구동형 능동 엔진 마운트의 설계)

  • Park, Hyun-Ki;Lee, Bo-Ha;Lee, Chong-Won
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.1106-1111
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    • 2007
  • This paper is focused on design of a new active control engine mount (ACM), which is compact in size and cost effective. The ACM, consisting of an electrodynamic actuator as the active element, flat springs and a sliding ball joint, is different in structure from the previous ACM designs based on the conventional hydraulic engine mount. Dynamic characteristics of the proposed ACM are extensively investigated before a prototype ACM, which meets the design specifications, is built in the laboratory. For cost effectiveness, a feed-forward control algorithm without a feedback sensor is used for reduction of the transmitted force through the ACM from the engine. The prototype ACM is then harmonic-tested with a rubber testing machine for verification of its control performance as well as adequacy of modeling. Experimental results show that the proposed ACM is capable of reducing the transmitted force by 20 dB up to the frequency range of 60 Hz.

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Adaptive Congestion Control Scheme of TCP for Supporting ACM in Satellite PEP System (위성 PEP시스템에서 ACM 지원을 위한 적응형 TCP 혼잡제어기법)

  • Park, ManKyu;Kang, Dongbae;Oh, DeockGil
    • Journal of Satellite, Information and Communications
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    • v.8 no.1
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    • pp.1-7
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    • 2013
  • Currently satellite communication systems usually use the ACM(Adaptive Coding and Modulation) to extend the link availability and to increase the bandwidth efficiency. However, when ACM system is used for satellite communications, we should carefully consider TCP congestion control to avoid network congestions. Because MODCODs in ACM are changed to make a packet more robust according to satellite wireless link conditions, bandwidth of satellite forward link is also changed. Whereas TCP has a severe problem to control the congestion window for the changed bandwidth, then packet overflow can be experienced at MAC or PHY interface buffers. This is a reason that TCP in transport layer does not recognize a change of bandwidth capability form MAC or PHY layer. To overcome this problem, we propose the adaptive congestion control scheme of TCP for supporting ACM in Satellite PEP (Performance Enhancing Proxy) systems. Simulation results by using ns-2 show that our proposed scheme can be efficiently adapted to the changed bandwidth and TCP congestion window size, and can be useful to improve TCP performance.

A Design of Automated Contingency Management and Case Study for Monopropellant Propulsion System (단일추진시스템의 ACM 설계 및 사례연구)

  • Lee, Young-Jin;Lee, Kwon-Soon;Vachtsevanos, George
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.16 no.2
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    • pp.1-11
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    • 2008
  • Increasing demand for improved reliability and survivability of mission-critical systems is driving the development of health monitoring and Automated Contingency Management (ACM) systems. An ACM system is expected to adapt autonomously to fault conditions with the goal of still achieving mission objectives by allowing some degradation in system performance within permissible limits. ACM performance depends on supporting technologies like sensors and anomaly detection, diagnostic/prognostic and reasoning algorithms. This paper presents the development of a generic prototype test bench software framework for developing and validating ACM systems for advanced propulsion systems called the Propulsion ACM (PACM) Test Bench. The architecture has been implemented for a Monopropellant Propulsion System (MPS) to demonstrate the validity of the approach. A Simulink model of the MPS has been developed along with a fault injection module. It has been shown that the ACM system is capable of mitigating the failures by searching for an optimal strategy. Furthermore, the concepts of Validation and Verification (V&V) of such systems are introduced with relevant examples.

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항공기용 ACM(Air Cycle Machine) 설계 및 공력성능시험

  • 현용익;김진한;김춘택;차봉준;이대성;김승우;천익정
    • 유체기계공업학회:학술대회논문집
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    • pp.58-73
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    • 1997
  • 본 연구는 항공기용 환경제어계통의 시스템관련 제반 기술 및 그 핵심요소인 ACM(Air Cycle Machine)시제기의 개발을 통하여 국내의 여런 항공기개발 사업과 관련하여 급속히 요구되고 있는 항공기의 sub-system을 국산화할 수 있는 기술축적을 목적으로 수행되었다. 본 연구에서는 항공기용 환경제어장치(Environmental Control System : ECS)를 개발대상으로 하여 그 핵심부품인 Air Cycle Machine의 시제품을 순수 국내 기술로 설계/제작하였고, 자체 개발한 성능시험기를 이용하여 성능시험을 수행하였으며 또한 ACM 성능을 검증하기 위하여 기존제품의 자료와 비교하였다. 향후 이 시스템의 상품화를 위해서는 구동축의 무윤활 베어링에 대한 연구가 병행되어 주유동의 오일오염을 국소화시키는 시스템보완이 요구된다. 항공기용 환경제어장치(ECS)의 시스템해석부터 ACM의 공력/구조설계, 제작, 시험등 일련의 개발과정을 통하여 시스템에 대한 해석능력이 향상되었고, 그 핵심요소인 ACM의 순수 국산화개발이 가능하다는 판단을 내릴 수 있었다. 또한, ACM을 구성하고 있는 원심압축기와 반경류형 터빈의 제작 및 시험법은 유사 시스템 및 일반 터보기계류의 국산화개발에 유용하게 이용될 것으로 기대된다.

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Characteristic Analysis of the Asymmetric Coupled microstrip Lines with finite Metalization Thickness in the Multilayered Structure (다층구조에서 도체 두께를 고려한 비대칭 결합선로의 특성해석)

  • 윤남일;홍익표;박한규
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.25 no.3A
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    • pp.424-429
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    • 2000
  • In this paper, the characteristics of the asymmetric coupled microstrip(ACM) lines with finite metalization thickness are investigated using the quasi-static analysis in the multilayered structure. By mode-matching method as the quasi-static analysis. the characteristic impedances and effective dielectric constants in ACM lines are obtained as a function of metalization thickness. The numerical results show that the propagation characteristics of ACM lines in the single and multilayered structure will be changed by the variation of metalization thickness.

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A Study on Prediction method for Forward link ACM of Satellite Communication Public Testbed via COMS (천리안 위성을 이용한 위성통신 공공 테스트베드 포워드링크 ACM 구축을 위한 예측기법 연구)

  • Ryu, Joon-Gyu;Hong, Sung-Yong
    • Journal of Satellite, Information and Communications
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    • v.7 no.1
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    • pp.82-85
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    • 2012
  • In this paper, we present the forward link ACM method to improve the link availability and system throughput. Also, we compare the prediction algorithm between slope based prediction and LMS algorithm. The simulation results show that the 99% of predicted values in LMS algorithm is within 3dB and that of predicted values in the slope based prediction method is within 4.5dB.

Studies on the structure-activity of antimicrobial peptide isolated from horseshoe crab (투구게로부터 단리된 항균성 펩티드의 구조-활성에 관한 연구)

  • Lee, Hyung-Ho;Park, Jang-Su;Park, Nam-Gyu
    • Journal of fish pathology
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    • v.9 no.1
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    • pp.65-77
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    • 1996
  • Tachyplesin I is an antimicrobial peptide isolated from horseshoe crab. To investigate the mechanism of action of tachyplesin I for phospholipid bilayers, tachyplesin I and five analogs have been synthesized by the solution method. The synthesized five analogs are [$Phe^2$]-tachyplesin I, [$Phe^{8,13}$]-tachyplesin I, [$Cys(Acm)^{3,7,12,16}$]-tachyplesin I with no disulfide bonds, 7(Acm) and 10 (Acm) which denote the fragments [$Cys(Acm)^{3,7,12,16}$]-tachyplesin I. Circular dichroism spectra showed that tachyplesin I took an antiparallel $\beta$-structure in buffer solution and a less ordered structure in acidic liposomes. The carboxyfluorescein leakage experiment indicated that tachyplesin I interacted strongly with neutral and acidic phospholipid bilayers. In fluorescence experiment, the hydrophobic part of the peptide was shown to be embedded in lipid bilayers. All the peptides except for 7(Acm) and 10(Acm) were almost equally active in lipopolysaccharide binding. Therefore, the present study suggested that phospholipid bilayers induced a conformational change of tachyplesin I from the stable $\beta$-structure to a less ordered one.

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Improvement of Domain-specific Keyword Spotting Performance Using Hybrid Confidence Measure (하이브리드 신뢰도를 이용한 제한 영역 핵심어 검출 성능향상)

  • 이경록;서현철;최승호;최승호;김진영
    • The Journal of the Acoustical Society of Korea
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    • v.21 no.7
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    • pp.632-640
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    • 2002
  • In this paper, we proposed ACM (Anti-filler confidence measure) to compensate shortcoming of conventional RLJ-CM (RLJ-CM) and NCM (normalized CM), and integrated proposed ACM and conventional NCM using HCM (hybrid CM). Proposed ACM analyzes that FA (false acceptance) happens by the construction method of anti-phone model, and presumed phoneme sequence in actuality using phoneme recognizer to compensate this. We defined this as anti-phone model and used in confidence measure calculation. Analyzing feature of two confidences measure, conventional NCM shows good performance to FR (false rejection) and proposed ACM shows good performance in FA. This shows that feature of each other are complementary. Use these feature, we integrated two confidence measures using weighting vector α And defined this as HCM. In MDR (missed detection rate) 10% neighborhood, HCM is 0.219 FA/KW/HR (false alarm/keyword/hour). This is that Performance improves 22% than used conventional NCM individually.