• 제목/요약/키워드: Success Run Test

검색결과 16건 처리시간 0.026초

1100℃급 가스터빈 동익의 무고장시험을 통한 HCF 신뢰성 평가 (Success Run Test for Reliability Demonstration of 1100℃ Gas Turbine Blades)

  • 이두영;구재량;김두수;김동환
    • KEPCO Journal on Electric Power and Energy
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    • 제3권2호
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    • pp.107-111
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    • 2017
  • $1100^{\circ}C$급 가스터빈 동익의 국산화 개발품에 대한 신뢰성을 무고장시험법에 의해 평가하였다. 터빈 동익은 기동, 정지 중에 발생하는 공진 또는 유체유발진동을 겪는 등 터빈 운전 중 상시 다양한 동하중에 노출되어 있으며, 이러한 변동하중은 터빈 동익에 고주기피로손상을 초래한다. 특히 동익의 파손에 의한 사고는 타 설비로의 파급이 크고, 막대한 경제적 피해를 야기하기 때문에, 발전소의 안정적인 운전을 위해 동익의 신뢰성이 우선 검증되어야 한다. 동익에 균열을 일으키기 위해서 전자식 가진기를 이용하여 공진에 의한 증폭된 동하중을 부과하였다. 가스터빈 동익의 수명분포를 와이블 분포로 가정하여 를 시험 시간을 계산하고, 시료 1개의 고장을 허용하는 조건으로 총 5개의 개발품을 대상으로 시험을 수행하여, 개발품 동익의 목표 수명을 90% 신뢰도로 보증할 수 있다는 것을 90% 신뢰수준에서 확인하였다.

장기소비 위험을 이용한 통화포트폴리오 수익률에 관한 연구 (A Study on the Long-Run Consumption Risk in Foreign Currency Risk Premia)

  • 유원석;손삼호
    • 유통과학연구
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    • 제11권10호
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    • pp.55-62
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    • 2013
  • Purpose - The purpose of this study is to suggest a risk factor that significantly explains foreign currency risk premia. In recent years, some studies have found that the performance of the simultaneous consumption risk model improves considerably when tested on foreign currency portfolios, which are constructed based on the international interest rates differentials. However, this paper focuses on the long-run consumption risk factor. In our empirical research, we found that the real excess returns of high interest rate currency portfolios depreciate on average, when the future American long-run consumption growth rate appears low. This makes the high interest rate currency portfolios have relatively high risk premia. Meanwhile, the real excess returns of low interest rate currency portfolios appreciate on average, under the same conditions, which results in relatively low risk premia for these portfolios. Therefore, this long-run consumption risk factor might explain why low interest rate currencies do not appreciate as much as the interest rate differential, and why high interest rate currencies do not depreciate as much as the interest rate differential. Research design, data, methodology - In our explanation, we provide new evidence on the success of long-run consumption risks in currency risk premia by focusing on the long-run consumption risks borne by American representative investors. To uncover the hidden link between exchange rates and long-run consumption growth, we set the eight currency portfolios as our basic assets, which have been built based on the foreign interest rates of eighty countries. As these eight currency portfolios are rebalanced every year, the first group always contains the lowest interest rate currencies, and the last group contains the highest interest rate currencies. Against these basic eight currency portfolios, we estimate the long-run consumption risk model. We use recursive utility framework and the stochastic discount factor that depends on the present value of expected future consumption growth rates. We find that our model is optimized in the two-year period of constructing the durable consumption expectation factor. Our main results surprisingly surpass the performance of the existing benchmark simultaneous consumption model in terms of R2, relatively risk aversion coefficient γ, and p-value of J-test. Results - The performance of our model is superior. R2, relatively risk aversion coefficient γ, and p-value of J-test of our long-run durable consumption model are 90%, 93%, and 65.5%, respectively, while those of EZ-DCAPM are 87%, 113%, and 62.8%, respectively. Thus, we can speculate that the risk premia in foreign currency markets have been determined by the long-run consumption risk. Conclusions - The aggregate long-run consumption growth risk explains a large part of the average change in the real excess returns of foreign currency portfolios. The real excess returns of high interest rate currency portfolios depreciate on average when American long-run consumption growth rate is low, and the real excess returns of low interest rate currency portfolios appreciate under the same conditions. Thus, the low interest rate currency portfolios allow investors to hedge against aggregate long-run consumption growth risk.

Gravitational-wave EM Counterpart Korean Observatory (GECKO): Network of Telescopes and Follow-up Result for S190425z

  • Paek, Gregory SungHak;Im, Myungshin
    • 천문학회보
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    • 제44권2호
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    • pp.76.2-76.2
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    • 2019
  • Recent observation of the neutron star merger event, GW170817, through both gravitational wave (GW) and electromagnetic wave (EM) observations opened a new way of exploring the universe, namely, multi-messenger astronomy (MMA). One of the keys to the success of MMA is a rapid identification of EM counterpart. We will introduce the strategy for prioritization of GW source host galaxy candidates. Our method relies on recent simulation results regarding plausible properties of GW source host galaxies and the low latency localization map from LIGO/Virgo. We will show the test results for both NS merger and BH merger events using previous events and describe observing strategy with our facilities for GW events during the ongoing LIGO/Virgo O3 run. Finally, we report the result of follow-up observation on, the first neutron star merger event, S190425z, during LIGO/VIrgo O3 run.

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유도무기 시험평가 방법과 신뢰성 성장을 고려한 시험 수량 산출 (Calculation of Sample Size for Guided Missile Considering Test Method and Reliability Growth)

  • 이연호;김재황;이계신;이종신;이명진;김두현
    • 한국군사과학기술학회지
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    • 제20권6호
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    • pp.844-852
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    • 2017
  • Since guided weapon is high-cost and one-shot device which is non-reusable, it requires a lot of resources to prove required accuracy as a part of reliability demonstration. Once a test for proving accuracy rate of guided missile fails, it causes an additional cost and delay of schedule. This study introduces an equation for proper sample size and plan for guided-missile accuracy rate test in order to minimize the risk of test failure. Proper sample size for the test is derived by considering the reliability growth. Furthermore, each task for accuracy rate test is defined according to the development step. Therefore, this study can contribute to reduce sample size for accuracy rate test in order to meet the reliability requirement and assure transparency in the test process.

A Send-ahead Policy for a Semiconductor Wafer Fabrication Process

  • Moon, Ilkyeong
    • 한국경영과학회지
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    • 제18권1호
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    • pp.119-126
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    • 1993
  • We study a manufacturing process that is quite common in semiconductor wafer fabrication of semiconductor chip production. A machine is used to process a job consisting of J wafers. Each job requires a setup, and the i$_{th}$ setup for a job is sucessful with probability P$_{i}$. The setup is prone to failure, which results in the loss of expensive wafers. Therefore, a tiral run is first conducted on a small batch. If the set up is successful, the test is passed and the balance of the job can be processed. If the setup is unsuccessful, the exposed wafers are lost to scrap and the mask is realigned. The process then repeats on the balance of the job. We call this as send-ahead policy and consider general policies in which the number of wafers that are sent shead depend on the cost of the raw wafer, the sequence of success probabilities, and the balance of the job. We model this process and determine the expected number of good wafers per job,the expected time to process a job, and the long run average throughput. An algorithm to minimize the cost per good wafer subject to a demand constraint is provided.d.d.

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공공교통 전동차 안전운행을 위한 RIMS 프로젝트 적용의 성공요인 연구 (A Study on the Successful Factors in the Application of RIMS Project for the Safe Operation of Rolling Stocks in the Public Transportation)

  • 이강원;방연근;손영진
    • 한국철도학회논문집
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    • 제9권5호
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    • pp.555-560
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    • 2006
  • This study finds out and suggests success factors for the application of RIMS project through the case study of Seoul Metro and literature survey. The successful application of RIMS needs expert knowledge and concept of BOM, standardization of maintenance planning, check lists of heavy maintenance inspection, organization structure of rolling stock maintenance offices, material management system of warehousing and the process of parts repairing between offices, connection of material ordering system, problem solving of circular spare parts administration among inspection, maintenance, and material organizational units, systemic serial number management of parts with RFID, daily closing diary connected with work process chart, and sufficient period of RIMS's test run. RIMS contributes to real time management of rolling stock maintenance, transparency of management, reliability of train operation, customer satisfaction, and management innovation.

Observing strategy for electromagnetic counterpart of gravitational wave source

  • Paek, Gregory SungHak;Im, Myungshin
    • 천문학회보
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    • 제44권1호
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    • pp.58.2-58.2
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    • 2019
  • Recent observation of the neutron star merger event, GW170817, through both gravitational wave (GW) and electromagnetic wave (EM) observations opened a new way of exploring the universe, namely, multi-messenger astronomy (MMA). One of the keys to the success of MMA is a rapid identification of EM counterpart through optical/NIR observations. We will present the strategy for prioritization of GW source host galaxy candidates to be observed with narrow-field optical telescopes. Our method relies on recent simulation results regarding plausible properties of GW source host galaxies and the low latency localization map from LIGO/Virgo. We will show the test results for both NS merger and BH merger events using previous events and possible future events and describe observing strategy with our facilities for GW events during the ongoing LIGO/Virgo O3 run.

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Gravitational-wave Electromagnetic Counterpart Korean Observatory (GECKO): Network of Telescopes and Follow-up Observation of GW190425

  • Paek, Gregory S.H.;Im, Myungshin
    • 천문학회보
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    • 제45권1호
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    • pp.36.3-37
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    • 2020
  • Recent observation of the neutron star merger event, GW170817, through both gravitational wave (GW) and electromagnetic wave (EM) observations opened a new way of exploring the universe, namely, multi-messenger astronomy (MMA). One of the keys to the success of MMA is a rapid identification of EM counterpart. We will introduce GW follow-up observation project in Korea for hunting GW EM counterpart rapidly and its strategy for prioritization of GW source host galaxy candidates. Our method relies on recent simulation results regarding plausible properties of GW source host galaxies and the low latency localization map from LIGO/Virgo. We will show a test result for both binary neutron star merger events using previous event and describe observing strategy with our facilities for GW events during the ongoing LIGO/Virgo O3 run. Finally, we report the results of optical/NIR follow-up observation of GW190425, the first neutron.

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고속회전시험기를 활용한 가스터빈 동익의 내구성 시험 (Spin Testing for the Endurance Verification of Gas Turbine Blades)

  • 이두영;김두수;손태하;구재량
    • KEPCO Journal on Electric Power and Energy
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    • 제4권1호
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    • pp.19-24
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    • 2018
  • 가스터빈 동익에 대한 지속적인 국산화 개발이 추진되어, 국내 정밀 주조 기술을 향상시키고, 동익의 유지 보수 비용을 낮추는 등의 직간접적인 긍정적 효과를 가져왔지만, 여전히 국산화 개발품이 발전소에서 안정적인 실사용이 가능한지에 대한 우려가 존재한다. 향상된 소재와 주조기술을 바탕으로 조직학적, 기계적 성질에서 충분한 품질을 확보하였더라도, 개발품을 대상으로 다양한 신뢰성 검증이 요구되는 이유이다. 고속회전시험기는 로터, 디스크 등의 회전체에 원심력을 가하여, 이에 따른 제품의 특성을 분석하기 위한 시험장비로 일반적으로 과속도시험을 통한 최종적인 품질검사에 주로 사용된다. 본 논문에서는 전력연구원에 구축된 고속회전시험기를 활용한 가스터빈 동익에 대한 과속도시험을 포함한 저주기피로시험 사례를 중심으로 신뢰성 시험 및 평가 결과를 기술하였다.

스포츠영재성 검사 항목과 코스타스 점수간의 연관성 분석 (Association analysis between sports talent test scores and KOSTASS scores)

  • 박철용;이미숙
    • Journal of the Korean Data and Information Science Society
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    • 제22권1호
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    • pp.57-64
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    • 2011
  • 이 연구에서는 최근 체육영재선정에 공통적으로 사용되고 있는 스포츠영재성 검사 항목과 코스타스 점수간의 연관성 분석을 통해 상대적으로 중요한 검사 항목과 그렇지 않은 검사 항목을 통계적으로 밝혀내는 데 목적이 있다. 이 연구를 위해 2010년도 서울지역 (강동구, 송파구, 노원구, 광진구 등)과 경기지역 (의정부시, 가평군, 구리시 등) H대학 체육영재양성사업에 지원한 201명의 초등학교 학생들의 자료가 사용되었으며, 육상 네 종목 (투척, 도약, 단거리, 중장거리), 수영 및 체조 종목의 코스타스 점수와 1차 스포츠영재성 검사에서 얻은 기본 체격, 체력 운동능력, 생리적 기능 정보를 이용하였다. 구체적으로 순수한 연관성 분석을 위해 피어슨상관계수와 편상관계수를 사용하였으며, 중요한 검사 항목 선택을 위해 단계적 회귀분석을 이용하였다. 그 결과 골연령, 체중, 흉위와 50m달리기, 하프스쿼트점프가 6개 코스타스 점수에 미치는 영향이 상대적으로 미약한 것으로 나타났다.