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Thermo-Mechanical Behavior of Short SMA Reinforced Polymeric Composite Using Shear tag Theory (전단지연 이론을 이용한 단섬유 형태의 SMA 보강 고분자 복합재료의 열변형 거동 해석)

  • Jeong, Tae-Heon;Lee, Dong-Joo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.23 no.6 s.165
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    • pp.1001-1010
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    • 1999
  • Thermo-mechanical behavior of discontinuous shape memory alloy(SMA) reinforced polymeric composite has been studied using modified shear lag theory and finite element(FE) analysis with 2-D multi-fiber model. The aligned and staggered models of short-fiber arrangement are employed. The effects of fiber overlap and aspect ratio on the thermomechanical responses such as the thermal expansion coefficient are investigated. It is found that the increase of both tensile stress(resistance stress) in SMA fiber and compressive stress in polymer matrix with increasing aspect ratio is the main cause of low thermal deformation of the composite.

The Change of Water Quality In Osaka Bay during Recent 70 Years

  • Han, Dong-Jin;Yoon, Jong-Sung
    • Journal of Environmental Science International
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    • v.13 no.11
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    • pp.1001-1007
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    • 2004
  • The rapid industrialization and urbanization in Osaka Bay have produced many serious water pollution problems since the 1960s. A symbolic phenomenon is algae bloom (red tide), which occurred 53 times in 1976. The special law was enacted in 1973 and a number of administrative steps were taken, such as cutting COD loading, reductions in phosphorus (P) and restriction of land reclamation. As a result, the pollution of Osaka Bay has gradually been reduced, and the environment has been improved to some extent. In this study, to analyze the relations between water qualities as well as a social, economic activity by the coastal zone, the water quality data in Osaka Bay of 70 years past since 1921 were collected. Data such as population, livestock, fertilizer, industrial product etc. were also collected for estimating nutrients flowing into bay from land. It was found that the water quality was changed of a similar trend of estimated nutrients load, with delay of about four or five years.

A Study on the Performance of a Short Term Ozone Passive Sampler in Experimental Chamber (단기 측정용 오존 간이 측정기의 실험 챔버 내에서 성능에 관한 연구)

  • Jeong, Sang-Jin
    • Journal of Environmental Science International
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    • v.16 no.8
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    • pp.1001-1009
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    • 2007
  • Passive sampler is a simple and cost-effective measuring equipment for ambient and indoor air pollution. We studied the performance of a short term (1 hour mean concentration) ozone passive sampler which was coated with a colorant (indigo carmine) to a filter substrate. Acetone and sulfamic acid added ozone passive sampler was investigated to measure short term mean ozone concentration. Ozone response and interference of criteria air pollutant($SO_2,\;NO_2$, CO) on a short term ozone passive sampler was tested through experimental chamber. The results show sulfamic acid added passive ozone sampler have good response in ozone exposure. Interference of $NO_2$ gas is larger than other two criteria gases.

CT Reconstruction using Discrete Cosine Transform with non-zero DC Components (영이 아닌 DC값을 가지는 Discrete Cosine Transform을 이용한 CT Reconstruction)

  • Park, Do-Young;Yoo, Hoon
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.63 no.7
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    • pp.1001-1007
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    • 2014
  • This paper proposes a method to reduce operation time using discrete cosine transform and to improve image quality by the DC gain correction. Conventional filtered back projection (FBP) filtering in the frequency domain using Fourier transform, but the filtering process uses complex number operations. To simplify the filtering process, we propose a filtering process using discrete cosine transform. In addition, the image quality of reconstructed images are improved by correcting DC gain of sinograms. To correct the DC gain, we propose to find an optimum DC weight is defined as the ratio of sinogram DC and optimum DC. Experimental results show that the proposed method gets better performance than the conventional method for phantom and clinical CT images.

Study for Injurious Multimedia Contents Analysis Mechanism in Smart Devices (스마트 기기에서 유해 멀티미디어 콘텐츠 판별 메커니즘 및 성능 분석)

  • Min, Sun-Ho;Kim, Seok-Woo;Ha, Kyeoung-Ju;Seo, Chang-Ho
    • Journal of the Korea Institute of Information Security & Cryptology
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    • v.23 no.6
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    • pp.1001-1006
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    • 2013
  • In this paper, Recently, we describe the distinction mechanism analysis and injurious distinction mechanism performance analysis in order to determine harmfulness of the injurious multimedia which is being rapidly spread in the smart phone and Intelligent Robots. Based on the injurious mechanism distinction technologies, We defined individual injurious characteristics elements of multimedia(images and videos). Also, We analyze harmfulness of the injurious multimedia content by the visual characteristics modeling.

Nonlinear ANC using a NPVSS-NLMS algorithm and online modelling of an acoustic linear feedback path (NPVSS-NLMS 알.고리즘과 온라인 선형 피드백 경로 모델링을 이용한 비선형 능동 소음 제어)

  • Seo, Jae-Beom;Nam, Sang-Won
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.59 no.5
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    • pp.1001-1004
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    • 2010
  • Acoustic feedback and background noise variation can degrade the performance of an active noise control (ANC) system. In this paper, nonlinear ANC using a non-parametric VSS-NLMS (or NPVSS-NLMS) algorithm and online feedback path modeling is proposed, whereby the conventional linear ANC with online acoustic feedback-path modeling is further extended to nonlinear Volterra ANC with a linear acoustic feedback path. In particular, the step-size of the NPVSS-NLMS algorithm is controlled to reduce the effect of background noise variation in the ANC system. Simulation results demonstrate that the proposed approach yields better nonlinear ANC performance compared with the conventional nonlinear ANC method.

Vibration analysis of a shear deformed anti-symmetric angle-ply conical shells with varying sinusoidal thickness

  • Javed, Saira;Viswanathan, K.K.;Aziz, Z.A.;Lee, J.H.
    • Structural Engineering and Mechanics
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    • v.58 no.6
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    • pp.1001-1020
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    • 2016
  • The study is to investigate the free vibration of antisymmetric angle-ply conical shells having non-uniform sinusoidal thickness variation. The arbitrarily varying thickness is considered in the axial direction of the shell. The vibrational behavior of shear deformable conical shells is analyzed for three different support conditions. The coupled differential equations in terms displacement and rotational functions are obtained. These displacement and rotational functions are invariantly approximated using cubic spline. A generalized eigenvalue problem is obtained and solved numerically for an eigenfrequency parameter and an associated eigenvector of spline coefficients. The vibration characteristic of the shells is examined for cone angle, aspect ratio, sinusoidal thickness variation, layer number, stacking sequence, and boundary conditions.

Compensation of Time Delay in Induction Motor Vector Control System Using DQ Transformation (유도전동기 벡터제어 시스템에서 DQ변환을 이용한 시간지연 보상)

  • 최병태;권우현;박철우
    • Journal of Institute of Control, Robotics and Systems
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    • v.9 no.12
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    • pp.1001-1008
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    • 2003
  • A time-delay compensation method for vector control system is proposed that can compensate for voltage and current distortions resulting from a time delay in the overall system due to the low pass filter, hysteresis control inverter, microprocessor program computation time, and so on. The proposed scheme estimates the time delay using the difference between the Q-axis stator current command and the time-delayed actual Q-axis stator current in a synchronous reference frame, then compensates the time delay in the voltage and current using the angular displacement of a DQ transformation. Accordingly, the proposed scheme can accurately compensate for the time delay related to the overall system, thereby significantly improving the performance of the vector control system, as verified by simulation and experiment.