• 제목/요약/키워드: Random Environment

검색결과 983건 처리시간 0.028초

BMAP(r)/M(r)/N(r) 대기행렬시스템 분석 (Analysis of BMAP(r)/M(r)/N(r) Type Queueing System Operating in Random Environment)

  • 김제숭
    • 대한산업공학회지
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    • 제42권1호
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    • pp.30-37
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    • 2016
  • A multi-server queueing system with an infinite buffer and impatient customers is analyzed. The system operates in the finite state Markovian random environment. The number of available servers, the parameters of the batch Markovian arrival process, the rate of customers' service, and the impatience intensity depend on the current state of the random environment and immediately change their values at the moments of jumps of the random environment. Dynamics of the system is described by the multi-dimensional asymptotically quasi-Toeplitz Markov chain. The ergodicity condition is derived. The main performance measures of the system are calculated. Numerical results are presented.

BMAP/M/N/O Queueing System in Random Environments

  • 김제숭
    • 한국품질경영학회:학술대회논문집
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    • 한국품질경영학회 2007년도 춘계학술대회
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    • pp.461-465
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    • 2007
  • The BMAP/M/N/O queueing system operating in Markovian random environment is investigated. The stationary distribution of the system is calculated. Loss probability and other performance measures are calculated. Numerical experiments which show the necessity of taking into account the influence of random environment and correlation in input flow are presented.

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DNAPL migration in fracture networks and its remediation

  • 이항복;지성훈;여인욱;이강근
    • 한국지하수토양환경학회:학술대회논문집
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    • 한국지하수토양환경학회 2003년도 추계학술발표회
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    • pp.543-547
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    • 2003
  • We applied the modified invasion percolation (MIP) model to the migration of DNAPL within a two-dimensional random fracture network. The MIP model was verified against laboratory experiments, which was conducted using a two-dimensional random fracture network model. The results showed that the MIP needs modification. To remove TCE trapped in a random fracture network, the density-surfactant-motivated removal method was applied and found very effective to remove TCE from dead-end fractures.

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DYNAMICAL MODEL OF A SINGLE-SPECIES SYSTEM IN A POLLUTED ENVIRONMENT

  • Samanta, G.P.;Maiti, Alakes
    • Journal of applied mathematics & informatics
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    • 제16권1_2호
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    • pp.231-242
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    • 2004
  • The effect of toxicants on ecological systems is an important issue from mathematical and experimental points of view. Here we have studied dynamical model of a single-species population-toxicant system. Two cases are studied: constant exogeneous input of toxicant and rapidly fluctuating random exogeneous input of toxicant into the environment. The dynamical behaviour of the system is analyzed by using deterministic linearized technique, Lyapunov method and stochastic linearization on the assumption that exogeneous input of toxicant into the environment behaves like ‘Coloured noise’.

해양환경 예측정보를 활용한 인공지능 분석 기반의 최적 안전항로 연구 (Research on optimal safety ship-route based on artificial intelligence analysis using marine environment prediction)

  • 엄대용;이방희
    • 한국항해항만학회:학술대회논문집
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    • 한국항해항만학회 2023년도 춘계학술대회
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    • pp.100-103
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    • 2023
  • 최근 스마트선박 개발에 발맞춰 정확하고 세밀한 실시간 해양환경 예측정보의 요구가 확대되고 선박에 직접 지원하기 위한 환경이 확보됨에 따라 최적항로 분야에서도 다양한 해양환경을 고려한 정보 생산 및 평가 연구가 필요하다. 스마트선박에서 해양환경의 위험도 및 에너지 소비의 불확실성을 줄이면서 최적항로를 산출할 수 있는 알고리즘은 2단계로 구분하여 개발하였다. 1단계는 해양환경정보들과 선박자동식별시스템(AIS)내에 선박의 위치·상태정보를 결합해 프로파일을 생성하였다. 2단계는 구성한 프로파일 결과를 이용하여 해양환경 에너지맵을 정의할 수 있는 모델을 개발하였고, 약 60만개의 데이터를 반영할 수 있도록 인공지능 머신러닝 기법 중 Random Forest를 적용하여 회귀식을 생성하였다. Random Forest 회귀 모델의 결정계수(R2)는 0.89 를 보였다. 생성한 모델에 2021년 6월 1일~3일의 해양환경 예측정보를 이용하여 Dijikstra 최단경로 알고리즘을 적용해 최적 안전항로를 산출하고 맵에 표출했다. Random Forest 회귀 모델로 산출된 항로는 유선적이고 해양환경 예측정보의 상태를 감안하며 항로를 도출하는 결과를 보였다. 본 연구의 실시간 해양환경 예측정보 기반의 항로 산출 개념은 선박의 이동 경향성을 반영한 현실적이면서 안전한 항로 산출이 가능하고, 향후 경제성, 안전성, 친환경성 평가 모델로 범위로 확대할 수 있을 것으로 기대된다.

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위성체 설계를 위한 랜덤 진동 해석 (Random Vibration Analysis for Satellite Design)

  • 이원범;김경원
    • 항공우주기술
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    • 제5권2호
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    • pp.102-107
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    • 2006
  • 본 논문은 위성체 동적 환경의 발사체 구조에 의해 전달된 저 주파수의 과도 진동과 불 규칙적인 가속력으로 구성되어 있다. 저 주파수에서의 과도 진동은 보통 진동수 100 ~ 200Hz에 이르는 정현파로 근사되며 주로 예비설계에 사용된다. 그리고, 랜덤 환경은 발사체의 연소와 분리 단계, 외부 공력소 음에 의한 구조적 진동에 의해 발생한다. 이는 발사체 구조물을 통하여 위성체와 발사체의 어댑터 구조로 전달된다. 이러한 동적환경 중에서 랜덤 진동 해석은 위성체에 수행되는데, 특히, 위성체 내의 전자 박스(장비) 는 실제 상황에 가깝게 하여 검증하기 위해 랜덤 진동 실험을 통해 설계 되야 한다.

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통신위성 중계기 부품의 진동특성 해석 (Vibration Characteristics Analysis of the Communication Satellite Transponder Equipment)

  • 김현수;이명규;박종흥;김성종;이영신
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2001년도 춘계학술대회논문집
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    • pp.374-379
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    • 2001
  • The satellite electronic equipment is exposed to high level random vibration environment during the launch of spacecraft. The random vibration can cause damage of electronic equipment. Thus very careful consideration on the launch environment, especially for high level random vibration, is required in the design stage of transponder equipments of communication satellite. For the structural integrity of the communication satellite transponder equipment under qualification level random vibration, Finite Element analysis was carried out using the commercial code, MSC/Nastran and ANSYS and stress levels are presented. In order to validate the femodel, modal test was also performed and compared with numerical results.

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지구관측위성의 발사환경시험 요구조건 (Launch Environment Requirements for Earth Observation Satellite)

  • 김경원;김성훈;김진희;이주훈;황도순
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2004년도 추계학술대회논문집
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    • pp.747-750
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    • 2004
  • After launching, spacecraft is exposed to extreme environments. So spacecraft should be tested after design/manufacture to verify whether components can be operated functionally. Acceleration transferred from launch vehicle to spacecraft produces quasi-static load, sine vibration and random vibration. Random vibration is also induced by acoustic vibrations transferred by surface of spacecraft. And shock vibration is produced when spacecraft is separated from launch vehicle. To verify operation of spacecraft under these launch environments, separation shock test, sine vibration test, acoustic vibration test and random vibration test should be performed. This paper describes these launch environment test requirements.

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Single Machine Sequencing With Random Processing Times and Random Deferral Costs

  • Park, Sung H.
    • 한국경영과학회지
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    • 제4권1호
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    • pp.69-77
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    • 1979
  • A single machine stochastic scheduling problem is considered. Associated with each job is its random processing time and random deferral cost. The criterion is to order the jobs so as to minimize the sum of the deferral costs. The expected sum of the deferral costs is theroretically derived under the stochastic situation for each of several scheduling decision rules which are well known for the deterministic environment. It is also shown that certain stochastic problems can be reduced to equivalent deterministic problems. Two examples are illustrated to show the expected total deferral costs.

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