• Title, Summary, Keyword: degrading characteristic

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Displacement Response of Degrading Systems to Near-Fault Ground Motions (근접-단층 지진에 대한 저하시스템의 변위응답)

  • 송종걸
    • Journal of the Earthquake Engineering Society of Korea
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    • v.4 no.2
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    • pp.1-12
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    • 2000
  • 단층에 근접한 지진동에 대하여 성능이 저하되는 단자유도계의 변위응답에 대하여 연구하였다 5% 의 감쇠비를 갖는 세단계의 성능저하시스템을 5개의 단층에 근접한 지진동에 대하여 해석하였다 해석결과로부터 성능저하시스템의 비탄성 변위응답은 비저하시스템에 비하여 큰 값을 나타냄을 알 수 있었다 또한 성능저하 특성이 증가할수록 변위응답은 커지는 경향이 있다 이러한 변위증폭은 구조물의 고유주기 강도와 성능저하특성에 영향을 받으며 짧은 주기영역에서는 큰 값을 나타내며 긴 주기영역에서는 변위증폭이 거의 발생하지 않는다 단층에 근접한 각각의 지진동에 대한 변위증폭의 최대값은 1초 보다 작은 주기영역에서 비저하시스템의 4배 정도이다 변위증폭계수의 평균값은 짧은 주기영역에서는 2의 값을 가지면 구조물의 고유주기가 길어질수록 1에 수렴해 감을 알 수 있었다.

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A Study on Reliability Prediction of System with Degrading Performance Parameter (열화되는 성능 파라메터를 가지는 시스템의 신뢰성 예측에 관한 연구)

  • Kim, Yon Soo;Chung, Young-Bae
    • Journal of the Society of Korea Industrial and Systems Engineering
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    • v.38 no.4
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    • pp.142-148
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    • 2015
  • Due to advancements in technology and manufacturing capability, it is not uncommon that life tests yield no or few failures at low stress levels. In these situations it is difficult to analyse lifetime data and make meaningful inferences about product or system reliability. For some products or systems whose performance characteristics degrade over time, a failure is said to have occurred when a performance characteristic crosses a critical threshold. The measurements of the degradation characteristic contain much useful and credible information about product or system reliability. Degradation measurements of the performance characteristics of an unfailed unit at different times can directly relate reliability measures to physical characteristics. Reliability prediction based on physical performance measures can be an efficient and alternative method to estimate for some highly reliable parts or systems. If the degradation process and the distance between the last measurement and a specified threshold can be established, the remaining useful life is predicted in advance. In turn, this prediction leads to just in time maintenance decision to protect systems. In this paper, we describe techniques for mapping product or system which has degrading performance parameter to the associated classical reliability measures in the performance domain. This paper described a general modeling and analysis procedure for reliability prediction based on one dominant degradation performance characteristic considering pseudo degradation performance life trend model. This pseudo degradation trend model is based on probability modeling of a failure mechanism degradation trend and comparison of a projected distribution to pre-defined critical soft failure point in time or cycle.

Noble measurement method for color breakup artifact in FPDs

  • Lee, Jong-Seo;Jun, Tae-Jong;Lee, Joo-Young;Han, Jung-Suk;Souk, Jun-H
    • 한국정보디스플레이학회:학술대회논문집
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    • pp.92-97
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    • 2006
  • Motion artifact of Display devices has a huge interest from industries and users recently. Among those artifacts, color break up (CBU) is one of the key degrading characteristic in field sequential type displays. Unfortunately, there are no objective measurement methods for CBU. Here we introduce two different kinds of CBU and its measurement methods. The CBU characteristic of LCD, DLP, and PDP was measured and compared.

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A Study on the Vibration Reduction and Performance Improvement of the CD/DVD is used from the Vehicle (자동차용 CD/DVD 데크의 진동 저감 및 성능 향상에 관한 연구)

  • Park, Young-Pil;Jung, Du-Han;Chung, Jin-Tal
    • Proceedings of the KSME Conference
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    • pp.799-804
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    • 2004
  • Dynamic characteristic of CD/DVD deck for vehicle is analyzed in this paper. Generally CD/DVD deck for vehicle is used from inferior environment with the vibration of the vehicle and shock of outside and so on. Therefore it must have the structure which is stabilized from the vibration to prevent read error. For this purpose, vibration characteristic of the deck for vehicle should be identified. To analyze characteristic of the deck system, we perform the signal analysis and modal testing using the FFT analyzer. Also we change the design factor degrading the performance of the deck system and verify the efficiency improvement using the acceleration measurement occurring to the sound discontinuation.

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Digital Image Watermarking using the Wiener Filter (위너 필터를 이용한 디지털 영상 워터마킹)

  • 이시중;김지영;고광식
    • Proceedings of the IEEK Conference
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    • pp.519-522
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    • 2000
  • Digital watermarking has been proposed as a solution to the problem of copyright protection of the multimedia documents. In this paper a new watermarking method for digital images operating in the frequency domain is proposed. In our approach, DCT coefficients of the watermark are added to the low frequency region of the host image, and extract it using the Wiener Filter. Due to the characteristic of the wiener filtering, the watermark is robust to various image processing techniques. Experimental results show that it is possible to reliably extract the watermark without degrading image quality.

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A Study on the Vibration Reduction and Performance Improvement of the CD/DVD for the Vehicles (자동차용 CD/DVD 데크의 진동 저감 및 성능 향상에 관한 연구)

  • Park Youngpil;Jung Duhan;Chung Jintai
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.29 no.7
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    • pp.1035-1041
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    • 2005
  • Dynamic characteristics of CD/DVD deck fur vehicle are analyzed in this paper. Generally CD/DVD deck for vehicle is used from inferior environment with the vibration of the vehicle, shock of outside and so on. Therefore it must have the structure which is stabilized from the vibration to prevent read error. For this purpose, vibration characteristic of the deck for vehicle should be identified. To analyze characteristic of the deck system, we perform the signal analysis and modal testing using the EFT analyzer. Also we change the design factor degrading the performance of the deck system and verify the efficiency improvement using the acceleration measurement occurring to the sound discontinuation.

Covariance Analysis Study for KOMPSAT Attitude Determination System

  • Rhee, Seung-Wu
    • International Journal of Aeronautical and Space Sciences
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    • v.1 no.1
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    • pp.70-80
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    • 2000
  • The attitude knowledge error model is formulated for specifically KOMPSAT attitude determination system using the Lefferts/Markley/Shuster method, and the attitude determination(AD) error analysis is performed so as to investgate the on-board attitude determination capability of KOrea Multi-Purpose SATellite(KOMPSAT) using the covariance analysis method. Analysis results show there is almost no initial value effect on Attitude Determination (AD) error and the sensor noise effects on AD error are drastically decreased as is predicted because of the inherent characteristic of Kalman filter structure. However, it shows that the earth radiance effect of IR-sensor(earth sensor) and the bias effects of both IR-sensor and fine sun sensor are the dominant factors degrading AD error and gyro rate bias estimate error in AD system. Analysis results show that the attitude determination errors of roll, pitch and yaw axes are 0.056, 0.092 and 0.093 degrees, respectively. These numbers are smaller than the required values for the normal mission of KOMPSAT. Also, the selected on-orbit data of KOMPSAT is presented to demonstrate the designed AD system.

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Characteristic of Chloride ion Diffusion in Mortar According to the Substitution Ratios of the Additive (혼합재 치환율에 따른 모르타르의 염소이온 확산 특성)

  • 양승규;정연식;이웅종;유재상;이종열
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.17-22
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    • 2002
  • Chloride ions have a tendency to penetrate into concrete and proceed the corrosion by depassivating rebar surface. Thus the deteriorated concrete is subject to experience severe degrading of durability under marine environment. Physical properties of mortar, such as, compressive strength and penetration depth of chloride ion were investigated. And to investigate the effect of containing SG, FA in mortar, the diffusion coefficient of chloride was measured through an electro - migration test. The diffusion coefficient of chloride was decreased with the increase of replacement ratio of SG compared with plain specimen.

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The General Characteristic of Elastic-Plastic Spectra (탄소성 응답스펙트럼의 일반적인 성질에 대하여)

  • 전규식
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • pp.233-240
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    • 1997
  • Seven kinds of hysteric model were used and classified three groups considering the absorbing capacities of strain energy for each model. Four kids of each model. Four kinds of strong motion earthquake record (two of them were recorded in Japan and the others in U.S.A) are used. The yield strength of building was set in the ratio to the maximum input acceleration (Yield Strength / Maximum Acceleration = 0.5~3.0). Natural periods of structures were varied 0.1~3.0 second with an interval of 0.1 second. First group : Elastic-Plastic model, Ramberg-Osgood model Second group : Degrading Tri-liner model, Takeda model Third group : Slip model, Origin model, Max-D model Elastic-plastic response spectra were calculated for response velocities, displacement, energy input, ductility factors, accumulated ductility factors. The equivalent response values of M.D.O.F systems against S.D.O.F system were calculated to compare the relationship of two systems.

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Degradation of Phenanthrene by Sphingomonas sp. 1-21 Isolated from Oil-Contaminated Soil

  • Ryeom, Tai-Kyung;Lee, Il-Gyu;Son, Seung-Yeol;Ahn, Tae-Young
    • Journal of Microbiology and Biotechnology
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    • v.10 no.5
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    • pp.724-727
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    • 2000
  • A Phenanthrene-degrading bacterium, Strain 1-21 was isolated from oil-contaminated soil. This strain was a Gram-negative, aerobic, and rod-shaped bacterium, and exhibited a 99% sequence similarity of 16S rDNA to that of Sphingomonas subarctica. The major cellular fatty acid was a summed feature 7(18:1 w7c, 18:1 w9t, 18:1 s12t), which is a characteristic of the Sphingomonas species. When 200 and 1,000 ppm of phenanthrene was added as the sole carbon source, Strain 1-21 degraded 98% and 67% after 10 days of incubation, respectively. Futhermore, this strain was also able to utilized naphthalene and fluorene as sole carbon and energy sources.

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