• Title/Summary/Keyword: 신뢰성(reliability)

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RAM Modeling and Analysis of Earth Observation Constellation Satellites (지구관측 군집위성의 RAM 모델링 및 분석)

  • Hongrae Kim;Seong-keun Jeong;Hyun-Ung Oh
    • Journal of Aerospace System Engineering
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    • v.18 no.1
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    • pp.11-20
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    • 2024
  • In the recent era of NewSpace, unlike high-reliability satellites of the past, low-reliability satellites are being developed and mass-produced at a lower cost to launch constellations satellites. To achieve cost-effective cluster satellite development, satellite users and developers need to assess the feasibility of maintaining mission performance over the expected lifespan when cluster satellites are launched. Plans for replacements due to random failures should also be established to maintain performance. This study proposed a method for assessing system reliability and availability to maintain mission performance and establish replacement strategies for Earth observation constellation satellites. In this study, a constellation reliability and availability model considering mission performance required for a satellite constellation, situations of satellite backup, and additional ground backups was established. The reliability model was structured based on the concept of a k-out-of-n system and the availability model used a Markov chain model. Based on the proposed reliability model, the minimum number of satellites required to meet mission requirements was defined and satellites needed in orbit during the required mission period to satisfy mission reliability were calculated. This research also analyzed the number of spare satellites in orbit and on the ground required to meet the desired availability during required service period through availability analysis.

A Study on the Judgment of Authoritative Records by Applying the Concept of Authenticity and Reliability (진본성, 신뢰성 개념을 적용한 공신력 있는 기록의 판단기준에 관한 연구)

  • Lee, Gemma;Oh, Kyung-Mook
    • Journal of Korean Society of Archives and Records Management
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    • v.20 no.3
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    • pp.77-97
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    • 2020
  • This study seeks to analyze the concepts of authenticity and reliability of records and apply them to the criteria for judging authoritative records subject to legal management. While reliability is determined by the degree of completeness and control in the records creation stage, authenticity is ensured by preventing manipulation and tampering that occur after records creation. Authoritative records with reliability in the creation stage are legally subject to management, so such records can be subject to punishment if they are destroyed because of negligence. It is necessary to take active measures to ensure reliability, continuous authenticity after creation, and complete records creation by controlled procedures and methods before records capture. The lack of such an evidential characteristic does not mean that it is not a record, and such records are also created in reality, managed in a system, and delivered to the next generation as a representation of social memory and activities.

Reliability Assessment Criteria of Power Amplifier for Mobile Phone (휴대폰용 전력증폭기의 신뢰성 평가기준)

  • Lee, Woo-Sung;Hwang, Soon-Mi;Lee, Kwan-Hun;Song, Byeong-Suk;Jeong, Hai-Sung;Oh, Geun-Tae
    • Journal of Applied Reliability
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    • v.9 no.3
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    • pp.233-248
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    • 2009
  • PAM(Power Amplifier Module) is the important part of a mobile phone transmitter. It amplifies the strength of signal transmitting from a mobile phone to base stations enough to resist noise or interference. In this paper reliability assessment criteria for the PAM are established in terms of quality certification test and lifetime test. The former quality certification test comprises general performance test and environmental test. Items which pass the test undergo lifetime test which guarantees the extent of mean lifetime with certain confidence.

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