• 제목/요약/키워드: Time Passage

검색결과 729건 처리시간 0.026초

Estimation of parameters including a quadratic failure rate semi-Markov reliability model

  • El-Gohary, A.;Alshamrani, A.
    • International Journal of Reliability and Applications
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    • 제12권1호
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    • pp.1-14
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    • 2011
  • This paper discusses the stochastic analysis and the statistical inference of a quadratic failure rate semi-Markov reliability model. Maximum likelihood procedure will be used to obtain the estimators of the parameters included in this reliability model. Based on the assumption that the lifetime and repair time of the system units are random variables with quadratic failure rate, the reliability function of this system is obtained. Also, the distribution of the first passage time of this system is derived. Many important special cases are discussed.

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On Convergence in p-Mean of Randomly Indexed Partial Sums and Some First Passage Times for Random Variables Which Are Dependent or Non-identically Distributed

  • Hong, Dug-Hun
    • Journal of the Korean Statistical Society
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    • 제25권2호
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    • pp.175-183
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    • 1996
  • Let $S_n,n$ = 1, 2,... denote the partial sums of not necessarily in-dependent random variables. Let N(c) = min${ n ; S_n > c}$, c $\geq$ 0. Theorem 2 states that N (c), (suitably normalized), tends to 0 in p-mean, 1 $\leq$ p < 2, as c longrightarrow $\infty$ under mild conditions, which generalizes earlier result by Gut(1974). The proof follows by applying Theorem 1, which generalizes the known result $E$\mid$S_n$\mid$^p$ = o(n), 0 < p< 2, as n .rarw..inf. to randomly indexed partial sums.

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Parameters Estimation of Generalized Linear Failure Rate Semi-Markov Reliability Models

  • El-Gohary, A.;Al-Khedhair, A.
    • International Journal of Reliability and Applications
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    • 제11권1호
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    • pp.1-16
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    • 2010
  • In this paper we will discuss the stochastic analysis of a three state semi-Markov reliability model. Maximum likelihood procedure will be used to obtain the estimators of the parameters included in this reliability model. Based on the assumption that the lifetime and repair time of the system units are generalized linear failure rate random variables, the reliability function of this system is obtained. Also, the distribution of the first passage time of this system will be derived. Some important special cases are discussed.

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경제적 LCC 를 위한 생산설비의 사용년수에 관한 연구 (A Study of Determination on Usage Life of Production Facilities for Economic LCC)

  • 유일근;박원준
    • 산업공학
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    • 제6권2호
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    • pp.37-51
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    • 1993
  • This paper studies the economic replacement method for production facilities which requires huge investment but are necessary for higher productivity and competability of products. That is, the general models for the decision of economic life of properties which minimizes the total costs throughout the usage life(Life cycle costs) are generated. Main factors which make influences for the decision of econmic life can be divided by three. These are the change of salvage value, repair and maintenance costs, and availability of production facilities with the passage of usage time. In this paper, the real world data for these three factors are collected and analyzed for the extraction of representative standard forms with the passage of time. And general models for economic replacement methods and optimal usage terms are presented through tables with the combination of the standard forms of these three main factors.

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포장방법에 따른 사슴고기의 냉장저장 중 이화화적 성질의 변화 (Changes in Physico-Chemical Properties of Deer Meat Packed Different ways During Storage at 4°C)

  • 신택순;이길왕;김선구;강한석;박현철;김근기
    • 생명과학회지
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    • 제17권3호통권83호
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    • pp.362-367
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    • 2007
  • 본 연구는 포장방법에 따른 사슴고기의 냉장저장 중 이화화적 성질의 변화에 대해 알아 보기 위하여 실시하였다. 생체중 220 $kg{\pm}10$ kg내외의 Elk 암컷 5마리를 도축하여 24시간 냉각한 후 발골하였고, 배최장근과 대퇴 근을 채취 하여 냉장온도로 25일간 유지하면서 비교 분석하였다. 보수성은 저장기간이 경과함에 따라 감소하는 경향이었고, 진공포장저장구가 보수성이 가장 낮았다. 저장기간이 경과함에 따라 TBARS가는 증가하였고, 진공포장저장구가 가장 낮은 TBARS가를 나타내었다. 저장기간이 경과함에 따라 VBN가는 증가하였고, 진공포장저 장구가 가장 낮은 VBN가를 나타내었다. pH는 저장기간이 경과함에 따라 증가하였고, 진공포장한 처리구가 가장 낮았다. 저장기간이 경과함에 따라 함기포장 처리구는 증가하였으나, 진공 포장처리구와 가스치환 포장처리구는 연도가 감소하였다. 대퇴근의 밝기는 포장방법에 따른 차이가 나타나지 않았고, 배최장근은 진공포장 처리구가 함기포장 처리구와 가스치환 포장처리구보다 유의적으로 밝았다. 대체적으로 진공포장 처리구가 함기포장 처리구와 가스치환 처리구보다 적색도가 높게 나타났다. 황색도는 저장기간 경과에 따라 증가 후 감소하는 경향을 나타내었고, 진공포장 처리구가 대체적으로 황색도 높았다.

WAITING TIME DISTRIBUTION IN THE M/M/M RETRIAL QUEUE

  • Kim, Jeongsim;Kim, Jerim
    • 대한수학회보
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    • 제50권5호
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    • pp.1659-1671
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    • 2013
  • In this paper, we are concerned with the analysis of the waiting time distribution in the M/M/m retrial queue. We give expressions for the Laplace-Stieltjes transform (LST) of the waiting time distribution and then provide a numerical algorithm for calculating the LST of the waiting time distribution. Numerical inversion of the LSTs is used to calculate the waiting time distribution. Numerical results are presented to illustrate our results.

전개판에 대한 수직해석 (Computational Fluid Analysis for the Otter Boards)

  • 고관서;권병국;노기덕
    • 수산해양기술연구
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    • 제28권2호
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    • pp.132-143
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    • 1992
  • This paper presents a method in order to calculate the vortex distribution, the streak-line and the time-line around the flat and the cambered otter board in two dimensional flow using the discrete vortex method, and to calculate C sub(L) and C sub(D) of the otter boards varied with the passage of time by the numerical simulation using the Blasu's formula. The results obtained are summarized as follows: 1. Flow pattern around the otter boards calculated by the discrete vortex method was resembled closely that of the visualized photograph. 2. C sub(L) and C sub(D) calculated by the numerical simulation was very similar to the model test. 3. The circulation direction around the otter boards and the action direction of the shearing force can be recognized from the time-line around the otter boards. 4. Flow speed in the back side of the otter boards was faster than that in the front side, and the difference of the flow speed in both side of the cambered otter boards was about 1.3 times greater than that of the flat otter boards. 5. The clockwise vortex was generated in the trailing edge, and the counter-clockwise vortex was generated the leading edge of the otter boards. And they were shown the shape of Karman's vortex varied with the passage of time.

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초음파 비파괴시험법을 이용한 데크재의 현장평가 (Ultrasonic Nondestructive On-Site Evaluation of Decks in-Service)

  • 오세창
    • Journal of the Korean Wood Science and Technology
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    • 제43권4호
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    • pp.486-493
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    • 2015
  • 설치된 데크재에 대한 성능을 평가하기 위하여 초음파 비파괴시험법을 사용하였다. 먼저 3종류의 데크재에 대해 트랜스듀서의 배치에 따른 직접법과 간접법간의 측정방법간의 차이를 검증하였으며 두 번째로 설치된 데크재의 사용시간의 경과에 따른 초음파속도를 측정 비교하였다. 마지막으로 데크재의 사용수명을 파악하기 위하여 사용시간의 경과에 따른 초음파속도의 변화를 조사하였다. 시험결과 직접법과 간접법간의 측정방법간의 차이는 없는 것으로 나타났으며 직접법에 대한 간접법의 비율은 1.02와 1.05로 각각 나타났다. 설치된 데크재에서 시간의 경과에 따라 초음파 속도는 감소하였으며 이들 간의 관계는 선형으로 나타났다. 시험결과로부터 초음파 비파괴시험법은 설치된 데크재의 유지보수에 관한 효율적인 수단이 될 수 있을 것으로 생각된다.

Foreign Body Ingestion in Children: Should Button Batteries in the Stomach Be Urgently Removed?

  • Lee, Jun Hee;Lee, Jee Hoo;Shim, Jung Ok;Lee, Jung Hwa;Eun, Baik-Lin;Yoo, Kee Hwan
    • Pediatric Gastroenterology, Hepatology & Nutrition
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    • 제19권1호
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    • pp.20-28
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    • 2016
  • Purpose: Foreign body (FB) ingestion is common in children, and button battery (BB) ingestion has been increasing in recent years. This study was to identify factors related to outcomes of FB ingestion, particularly BBs in the stomach. We evaluated whether the current recommendations are appropriate and aimed to suggest indications for endoscopic removal of BB in the stomach in young children. Methods: We investigated patient age, shape, size, location of FBs, spontaneous passage time and resulting complications among 76 children. We observed types, size, location of BB and outcomes, and analyzed their associations with complications. Results: Coins and BB were the two most common FBs. Their shapes and sizes were not associated with the spontaneous passage time. Size, spontaneous passage time, and age were also not associated with any specific complications. For BB ingestion, all 5 cases with lithium batteries (${\geq}1.5cm$, 3 V) presented moderate to major complications in the esophagus and stomach without any symptoms, even when the batteries were in the stomach and beyond the duodenum, while no complications were noted in 7 cases with alkaline batteries (<1.5 cm, 1.5 V) (p=0.001). All endoscopies were conducted within 24 hours after ingestion. Conclusion: The type and voltage of the battery should be considered when determining whether endoscopy is required to remove a BB in the stomach. For lithium battery ingestion in young children, urgent endoscopic removal might be important in order to prevent complications, even if the child is asymptomatic and the battery is smaller than 2 cm.

여수항 묘도수로 개선에 관한 연구 (Improvement Plan for Myodo-Strait at Yeosu Port)

  • 이창현;이홍훈;권유민
    • 해양환경안전학회지
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    • 제27권6호
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    • pp.775-782
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    • 2021
  • 여수항 묘도수도는 위험물 정제품을 운반하는 위험화물운반선의 주요 선박통항로로 이용되고 있다. 현재 묘도수로에서는 단독통항만을 허용하고 있고 통항 속력 또한 8노트로 제한되어 있다. 이로 인하여 위험물 정제품 부두에서의 체선료 또한 증가 추세에 있다. 향후 다수의 위험물 정제품 부두의 개발로 인하여 대상해역의 이용선박은 더욱 대형화되고 선박통항량 또한 증가될 것으로 예상하고 있다. 따라서 묘도수로를 이용하는 선박의 안전성 확보 및 체선료 개선을 위해서 묘도수로의 개선이 시급한 시점이다. 본 연구에서는 묘도수로의 해상환경 분석 및 해역 이용자 의견수렴 과정을 통하여 묘도수로의 개선안을 제시하였으며, 항만설계기준 검토 및 선박조종 시뮬레이션 평가를 통하여 항로 폭을 300m로 확장하고 수심 9.50m로 확보하는 방안을 최종적으로 제시하였다. 또한 해상교통혼잡도 평가 결과 현재 단독통항만이 허용되고 있는 상황에서 피크타임 해상교통혼잡도는 71.01%에서 교행이 허용되는 상황에서도 47.3%로 크게 개선되는 것으로 평가되었다. 제시한 묘도수로 개선방안에 따라 대상해역에서의 선박 통항안전성을 확보할 수 있으며, 체선료 문제 또한 개선될 것으로 판단되었다.