• Communications for Statistical Applications and Methods
• /
• 제12권2호
• /
• pp.483-496
• /
• 2005

We consider the power law process which is assumed to have multiple changepoints. We propose a binary segmentation procedure for locating all existing changepoints. We select one model between the no-changepoints model and the single changepoint model by the Bayes factor. We repeat this procedure until no more changepoints are found. Then we carry out a multiple test based on the Bayes factor through the intrinsic priors of Berger and Pericchi (1996) to investigate the system behaviour of failure times. We demonstrate our procedure with a real dataset and some simulated datasets.

• 한국안전학회지
• /
• 제29권6호
• /
• pp.166-171
• /
• 2014

Nuclear power plants are equipped with the reactor trip system (RTS) and the engineered safety features actuation system (ESFAS) to improve safety on the normal operation. In the event of the design basis accident (DBA), a various of post accident monitor(PAM)systems support to provide important details (e.g. Containment pressure, temperature and pressure of reactor cooling system and core exit temperature) to determine action of main control room (MCR). Operator should be immediately activated for the accident mitigation with the information. Especially, core exit temperature is a critical parameter because the operating mode converts from normal mode to emergency mode when the temperature of core exit reaches $649^{\circ}C$. In this study, uncertainty which was caused by exterior environment, characteristic of thermocouple/connector and accuracy of calibrator/indicator was evaluated in accordance with ANSI-ISA 67.04. The square root of the sum of square (SRSS) methodology for combining uncertainty terms that are random and independent was used in the synthesis. Every uncertainty that may exist in the hardware which is used to measure the core exit temperature was conservatively applied and the associative relation between the elements of uncertainty was considered simultaneously. As a result of uncertainty evaluation, the channel statistical allowance (CSA) of single channel of core exit temperature was +1.042%Span. The range of uncertainty, -0.35%Span ($-4.05^{\circ}C$) ~ +2.08%Span($24.25^{\circ}C$), was obtained as the operating criteria of core exit temperature.

• 디지털융복합연구
• /
• 제12권3호
• /
• pp.211-218
• /
• 2014

최근 풍력에너지는 풍력터빈의 지능화뿐만 아니라 풍력 발전량 예측 부분에서 컴퓨팅과의 결합이 확대되고 있다. 풍력 발전은 기상상태에 따라 출력변동이 심하고 출력 예측이 어려워 효율적인 전력 생산을 위해서 신재생에너지를 전력계통에 안정적으로 연계할 수 있는 기술이 필요하다. 본 논문에서는 분산형 전원의 예측정보를 향상시켜 예측한 발전량과 실제 발전량의 차이를 최소화하기 위한 분산형 전원전력의 단기예측 모델을 설계한다. 제안된 모델은 단기 예측을 위해서 물리모델과 통계모델을 결합하였으며, 물리모델에서 생산된 격자별 예측값 중 예측 지점내 예측지점의 값을 추출하고, 물리 모델 예측값에 통계모델을 적용하여 발전량 산정을 위한 최종 기상 예측값을 생성한다. 또한, 제안 모델에서는 실시간 기상청 관측자료와 실시간 중기 예측 자료를 입력 자료로 사용하여 단기 예측모델을 수행한다.

• 환경영향평가
• /
• 제29권4호
• /
• pp.272-285
• /
• 2020

본 연구에서는 3차원 기상 및 대기질 모델의 입출력 자료를 평가하는 데 필요한 통계 검증지표를 선별하고, 선정된 검증지표의 기준치를 조사하여 그 결과를 요약하였다. 여러 국내외 문헌과 최근 논문 검토를 통해 최종 선정된 통계 검증지표는 MB (Mean Bias), ME (Mean Error), MNB (Mean Normalized Bias Error), MNE (Mean Absolute Gross Error), RMSE (Root Mean Square Error), IOA (Index of Agreement), R (Correlation Coefficient), FE (Fractional Error), FB (Fractional Bias)로 총 9가지이며, 국내외 문헌을 통해 그 기준치를 확인하였다. 그 결과, 기상모델의 경우 대부분 MB와 ME가 주요 지표로 사용되어 왔고, 대기질 모델 결과는 NMB와 NME 지표가 주로 사용되었으며, 그 기준치의 차이를 분석하였다. 아울러 이들 통계 검증지표값을 이용하여 모델 예측 결과를 효과적으로 비교하기 위한 표출 도식으로 축구 도식, 테일러 도식, Q-Q (Quantile-Quantile) 도식의 장단점을 분석하였다. 나아가 본 연구 결과를 기반으로 우리나라의 산악지역의 특수성 등이 잘 고려된 통계 검증지표의 기준치 설정 등의 추가연구가 효과적으로 진행될 수 있기를 기대한다.

• Journal of Preventive Medicine and Public Health
• /
• 제32권1호
• /
• pp.80-87
• /
• 1999

Objectives. The Study of Small Area Variation(SAV) is most interesting issue in the health care researches. Most studies of SAV have been concluded the existences of variation on the basis of the magnitude of variation without statistical testing. But it is difficult to explain the existence of variation with this way because variation indicies are easily influenced by several parameters and also their distribution are skewed. So, it needs for the study to investigate the distribution of these indices and develop the statistical testing model. Methods. This study was planned to analyze on the distribution of variation indices such as Extremal Quotient(EQ), Coefficient of Variation(CV), Systematic Component of Variation(SCV) and compare the statistical power among indicies. The simulations was performed on the basis of several assumptions and compared to the empirical data. Results. Main findings can be summarized as follows. 1. If other conditions are constant, the more number of regions, the larger 95 percentile of EQ. But under same situation, 95 percentile of CV and SCV were slightly decreased. 2. If the size of regional population or utilization rate were increased, 95 percentile of all statistics were decreased. Also in the cases of small population size and low utilization rate, 95 percentiles of EQ showed various change contrast to the little change of CV. 3. If the difference at the size of regional population were increased, 95 percentiles of EQ and SCV were increased contrast to the little different of CV. 4. If the utilization rate were increased, 95 percentiles of all indicies were increased. But under the same difference of utilization rate, the power of CV and SCV were increased comparing to no change of the power of EQ. 5. Usually the power of EQ were lower than that of CV or SCV and it is similar between CV and SCV. Conclusions. Therefore, we suggest that in selecting the variation indicies at the SAV, CV or SCV are superior than EQ in terms of significance level and power.

• Communications for Statistical Applications and Methods
• /
• 제4권1호
• /
• pp.229-241
• /
• 1997

We consider discrimination curve and minimum dwell time for Poisson distribution and Poisson-power function distribution. Let the random variable X has Poisson distribution with mean .lambda.. For the hypothesis testing H$\_$0/:.lambda. = t vs. H$\_$1/:.lambda. = d (d$\_$0/ if X.leq.c. Since a critical value c can not be determined to satisfy both types of errors .alpha. and .beta., we considered discrimination curve that gives the maximum d such that it can be discriminated from t for a given .alpha. and .beta.. We also considered an algorithm to compute the minimum dwell time which is needed to discriminate at the given .alpha. and .beta. for the Poisson counts and proved its convergence property. For the Poisson-power function distribution, we reject H$\_$0/ if X.leq..'{c}.. Since a critical value .'{c}. can not be determined to satisfy both .alpha. and .beta., similar to the Poisson case we considered discrimination curve and computation algorithm to find the minimum dwell time for the Poisson-power function distribution. We prosent this algorithm and an example of computation. It is found that the minimum dwell time algorithm fails for the Poisson-power function distribution if the aiming error variance .sigma.$\^$2/$\_$2/ is too large relative to the variance .sigma.$\^$2/$\_$1/ of the Gaussian distribution of intensity. In other words, if .ell. is too small, we can not find the minimum dwell time for a given .alpha. and .beta..

• Communications for Statistical Applications and Methods
• /
• 제29권6호
• /
• pp.709-719
• /
• 2022

Recently, as the importance of environmental protection has emerged, interest in new and renewable energy is also increasing worldwide. In particular, the solar energy sector accounts for the highest production rate among new and renewable energy in Korea due to its infinite resources, easy installation and maintenance, and eco-friendly characteristics such as low noise emission levels and less pollutants during power generation. However, although climate prediction is essential since solar power is affected by weather and climate change, solar radiation, which is closely related to solar power, is not currently forecasted by the Korea Meteorological Administration. Solar radiation prediction can be the basis for establishing a reasonable new and renewable energy operation plan, and it is very important because it can be used not only in solar power but also in other fields such as power consumption prediction. Therefore, this study was conducted for the purpose of improving the accuracy of solar radiation. Solar radiation was predicted by a total of three weather variables, temperature, humidity, and cloudiness, and solar radiation outside the atmosphere, and the results were compared using various models. The CatBoost model was best obtained by fitting and comparing the Boosting series (XGB, CatBoost) and RNN series (Simple RNN, LSTM, GRU) models. In addition, the results were further improved through Time series cross-validation.

• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
• /
• 제15권7호
• /
• pp.469-477
• /
• 2009

제한된 용량의 배터리로 동작해야 하는 모바일 시스템에서는 소프트웨어 설계시 성능뿐만 아니라 전력소모도 고려해야 한다. 따라서 소프트웨어의 실행 중에 전력소모를 정확하게 예측할 수 있으면 전력과 성능을 고려한 효율적인 소프트웨어의 설계가 가능해진다. 본 논문에서는 모바일 프로세서의 전력소모 예측을 위해 정량적으로 프로세서의 동작을 분석하고 모델링 하는 통계적인 분석 방법을 제안한다. 제안된 방식은 다양한 벤치마크 프로그램들을 실행하여 프로세서의 성능 모니터링 이벤트들과 전력소모 데이터를 수집한 후 계층적 클러스터링(hierarchical clustering) 분석 등을 적용하여 서로 중복되지 않으면서 전력소모에 크게 기여하는 대표적인 성능 모니터링 이벤트들을 추출한다. 전력 예측 모델은 선택된 성능 모니터링 이벤트들이 독립변수가 되고 전력소모가 종속변수가 되는 회귀분석(regression analysis)을 수행하여 개발한다. 전력 예측 모델은 Intel XScale 아키텍처 기반의 PXA320 모바일 프로세서에 적용하여 평균 4% 이내의 에러율로 전력소모를 예측할 수 있음을 보인다.

• 한국인터넷방송통신학회논문지
• /
• 제18권6호
• /
• pp.181-186
• /
• 2018

산업화의 추세에 따라 수요가 급증하고 있는 고전력을 생산하기 위하여 시설장비 및 부하의 대용량화가 수반되고 있다. 전기설비의 규모는 점차 복잡해 지고, 대규모화 됨으로써 고도 정보화 사회로의 발전에 크게 기여하고 있다. 그러나, 발전 설비에서 불의의 사고가 발생하여 전기의 생산이 중단된다면, 전기에 의존하여 작동 중인 수 많은 장비가 지장을 받게되고, 산업사회에 막대한 경제적 손실 및 장애를 초래하게 된다. 사고가 발생한 발전설비를 복구하기 위해서는 많은 시간과 비용이 소요되어 국가 산업 활동에 막대한 경제적 피해를 끼치게 된다. 사고를 미연에 방지하기 위하여 케이블의 동작 상태를 정기적으로 감시 확인하여야 한다. 우리는 사고가 가장 빈번하게 발생하는 접속부에 대해 안정적인 사용을 위한 진단의 정확성과 신뢰성을 향상시키기 위한 연구를 하였다. 이 논문에서 데이터 취득을 하고, 통계적 처리를 하기 위한 방법을 제시한다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2003년도 하계학술대회 논문집 A
• /
• pp.667-669
• /
• 2003

Since the restructuring in electricity industry, single utility company, KEPCO, was being unbundled horizontanly and vertically, which resulted in 6 generation companies. Hence, electricity statistics system leaded by KEPCO is no longer efficiently sustainable. By introduction of electricity market, the importance of statistical information is getting higher and higher. From now on, the leading role played in statistical system in electricity field should be switched from KEPCO to government. This paper looks into change in statistical work driven by electricity and provides alternatives applicable to new electricity market. In addition, this paper provides new standard form for the collection of statistical data and construction of statistical system.