• 제목/요약/키워드: Sliding distance

검색결과 266건 처리시간 0.026초

직립방파제의 케이슨 활동에 대한 확률과정에 기반한 시간의존 신뢰성 설계법 개발 (Development of Time-Dependent Reliability-Based Design Method Based on Stochastic Process on Caisson Sliding of Vertical Breakwater)

  • 김승우;천세현;서경덕
    • 한국해안·해양공학회논문집
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    • 제24권5호
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    • pp.305-318
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    • 2012
  • 직립 케이슨 방파제에 대한 기존의 성능설계법은 임의의 시간 동안의 평균활동량을 산정하지만 허용활동량을 최초로 초과하는 사건의 발생확률(최초통과확률)은 계산하지 못한다. 설계자는 구조물이 최초로 피해를 입을 확률에 대한 정보를 구조물의 설계 단계뿐 아니라 관리 및 운영에서도 필요로 한다. 따라서 본 연구에서는 케이슨 활동의 최초통과확률을 산정하기 위해 확률과정에 기반한 시간의존 신뢰성 설계법을 개발하였다. 방파제의 활동을 일으키는 폭풍파는 발생 시간과 강도의 임의성의 특징이 있기 때문에 Poisson spike process를 사용하여 케이슨 활동을 정식화할 수 있다. 여기서 방파제의 활동을 일으키는 폭풍파의 발생률은 활동량분포함수와 폭풍파의 평균발생률로 표현된다. 성능설계법으로 모의된 이들은 설계변수들의 다변량 회귀함수로 나타내진다. 결과적으로 활동량분포함수와 폭풍파의 평균발생률은 유의파고, 케이슨 폭, 수심의 함수로 표현되어 케이슨 활동에 대한 최초통과확률을 손쉽게 산정할 수 있다.

Distance Functions to Detect Changes in Data Streams

  • Bud Ulziitugs;Lim, Jong-Tae
    • Journal of Information Processing Systems
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    • 제2권1호
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    • pp.44-47
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    • 2006
  • One of the critical issues in a sensor network concerns the detection of changes in data streams. Recently presented change detection schemes primarily use a sliding window model to detect changes. In such a model, a distance function is used to compare two sliding windows. Therefore, the performance of the change detection scheme is greatly influenced by the distance function. With regard to sensor nodes, however, energy consumption constitutes a critical design concern because the change detection scheme is implemented in a sensor node, which is a small battery-powered device. In this paper, we present a comparative study of various distance functions in terms of execution time, energy consumption, and detecting accuracy through simulation of speech signal data. The simulation result demonstrates that the Euclidean distance function has the highest performance while consuming a low amount of power. We believe our work is the first attempt to undertake a comparative study of distance functions in terms of execution time, energy consumption, and accuracy detection.

컨테이너 크레인용 레일클램프의 U형 쐐기 형상설계 (Shape Design of the U-Type Wedge of the Rail Clamp for a Container Crane)

  • 한동섭;한근조
    • 동력기계공학회지
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    • 제13권6호
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    • pp.117-122
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    • 2009
  • The wedge type rail clamp compresses the rails with small clamping force at first, and with large clamping force when the wind speed increases because of the wedge working. If the supporter is not installed in the rail clamp with V-type wedge when the wind speed increases more and more, the structure will occur overload which leads the structure to fracture. But in the clamp with U-type wedge the supporter is not necessary because the tangential angle of the wedge increases as the sliding distance increases. The proper shape of U-type wedge is determined by the initial clamping force and the tangential angle of the wedge. Accordingly we, first carry out the finite element analysis in order to analyze the relation between the sliding distance and the wedge angle. Next we suggest the proper shape of U-type wedge as analyze the relation between the radius of curvature and the sliding distance.

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PECVD에 의한 TiN 코팅의 마모특성 연구 (Wear Characteristics of TiN Coating by Plasma Enhanced CVD)

  • 송건;안효석
    • Tribology and Lubricants
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    • 제6권1호
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    • pp.116-125
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    • 1990
  • An experimental programme was established to determine the wear behaviour of TiN coatings of thickness 1 $\mu$m and 3 $\mu$m. by PECVD with the variation of applied load, sliding velocity and sliding distance. It was shown that oxidation of transferred metal as sliding speed increased formed oxide film so that it contributed in decreasing the wear rate. With the roller-on-disc tribometer employed, the wear rate of the roller specimen was decreased with the increase in sliding distance due to the reduction in effective contact pressure. Finally, the severe cracks concentrated at the trailing edge of contact surface were explained in terms of high tensile stress prevailing at the trailing edge of the contact and were identified as a dominant wear mechanism as well as the strong local welding between coating layer and the counter surface, leading to the debonding of the coating layer.

베어링 강(STB2)의 마멸에 미치는 알루미나 세라믹스의 마멸기구 (A Study on the Wear Mechanism of the Alumina Ceramics for the Wear of STB2)

  • 남준우;전태옥;진동규
    • 한국정밀공학회지
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    • 제12권3호
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    • pp.62-72
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    • 1995
  • The present study was undertaken to investigate the dry wear mechanism of the alumina ceramics in the purity variation for the wear of STB2. The wear test was carried out under different experimental condition various sliding speed, contact pressure and sliding distance. According as the alumina purity increased, wear volume of the STB2 decreased and minimum value of wear volume was over to high speed side. According as the sliding speed and sliding distance increased, friction coefficient decreased owing to drop of the shear strength, it decresed largely owing to decreased of elastic modulus and thermal conductivity with decrease in alumina purity. Indicative of minimum, value of wear volume, low speed side was abrasive wear, high speed side was wear of heat softening. The friction surface of ceramics protacted by oxide was transfer from STB2.

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Fe-17M 합금의 상에 따른 미끄럼 마멸 거동의 변화 (Sliding Wear Characteristics of the Fe-17Mn Alloy with Various Phases)

  • 이종은;김용석
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2005년도 춘계학술대회 논문집
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    • pp.411-414
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    • 2005
  • It is reported that $\varepsilon$ (HCP) and $\gamma$ (FCC) phases of a Fe-17Mn alloy transform to $\alpha'$ phase, which has BCC structure, under a deformation condition. In this study, we investigated the effect of strain-induced-transformed $\alpha'$ phase on sliding wear of the Fe-17Mn alloy that originally had e and y phases. Wear tests of the materials were carried out using a pin-on-disk wear tester at various loads of 0.5N-50N under a constant sliding speed condition of 0.38m/s against glass $(83\%\;SiO_2)$ beads. The sliding distance and radius were loom and 9 mm, respectively. Wear rate of the Fe-17Mn alloy was calculated by dividing the weight loss, measured to the accuracy of $10^{-5}g$ by the measured specific gravity and sliding distance. Worn surface and wear debris of the specimens were examined using an SEM and XRD. During the wear, $\alpha'$ phase of BCC structure was formed by strain-induced transformation when the applied wear load exceeded critical values. The $\alpha'$ phase formed by the strain induced transformation increased the wear rate of the Fe-17Mn alloy.

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FRP선박 외판재의 충격 및 마모 거동 (Impact and Wear Behavior of Side Plate of FRP Ship)

  • 김형진;김재동;고성위;김영식
    • 동력기계공학회지
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    • 제13권6호
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    • pp.123-128
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    • 2009
  • The effects of temperature and initial crack length on the impact fracture behavior for the side plate material of FRP ship were investigated. And the effects of the counterpart roughness and sliding distance on the volumetric wear of same material were investigated as well. Impact fracture toughness of GF/PE composites displayed maximum value when the temperature of specimen is room temperature and $50^{\circ}C$, and with decreasing the temperature of specimen, impact fracture toughness decreased. Impact fracture energy of GF/EP composites decreased with increasing the initial crack length of specimen, and this value decreased rapidly when the temperature of specimen is lowest, $-25^{\circ}C$. It is believed that sensitivity of notch on impact fracture energy were increased with decreasing the temperature of specimen. With increasing the sliding distance, the transition sliding distance, which displayed different aspect on the friction coefficient and the volumetric wear loss, were found out. Counterpart roughness had a big influence on the wear rate at running in period, however the effect of counterpart roughness became smaller with sliding speed increase in. Volumetric wear loss were increased with increasing the applied load and the counterpart roughness.

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고차 시스템을 위한 근궤적을 따르는 시변 슬라이딩 모드 (Time-Varying Sliding Mode Following Root Locus for Higher-Order Systems)

  • 김가규;최봉열
    • 제어로봇시스템학회논문지
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    • 제5권4호
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    • pp.379-384
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    • 1999
  • In this paper, we present a new time-varying sliding surface to achieve fast and robust tracking of higher-order uncertain systems. The surface passes through an initial error, and afterwards, it moves towards a predetermined target surface by means of a variable named by sliding surface gain and its intercept. Specifically, the sliding surface gain is determined so that its initial value can minimize a shifting distance of the surface and that the system roots in sliding mode can follow certain stable trajectories. The designed sliding mode control forces the system errors to stay always on the proposed surface from the beginning. By this means, the system remains insensitive to system uncertainties and disturbances for the whole time. To illustrate the effectiveness of the proposed method, the comparative study with conventional time-invariant sliding mode control is performed.

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6061AI 복합재료 마모특성에 미치는 SiC입자 강화재 체적분율의 영향 (Effect of Volume fraction of SiC Particle Reinforcement on the Wear Properties of 6061AI Composites)

  • 김헌주
    • 열처리공학회지
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    • 제15권2호
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    • pp.82-92
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    • 2002
  • In the present investigation wear behavior of the 6061AI composites reinforced with 5, 10, 20% SiC particles for dry sliding against a SM45C counterface was studied as a function of load and sliding velocity. Sliding wear tests were conducted at two loads(19.6 and 49N) and three sliding velocities(0.2, 1 and 2 m/sec) at constant sliding distance of 4000 m using pin-on-disk machine under room temperature. Presence of SiC reinforcement particles in the composites has displayed a transition from mild to severe wear at relatively higher applied load and sliding velocity compare to that of the matrix metal. As the volume fraction of SiC particles increased, the transition moved to a more severe wear conditions. Eventually, mild wear prevailed at a most severe wear conditions in this study, that was 49N load and 2 m/sec sliding velocity in 20% SiC particle/6061AI composite.