• 시스템엔지니어링학술지
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• 제19권2호
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• pp.18-31
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• 2023

Exploring artificial intelligence and machine learning for nuclear safety has witnessed increased interest in recent years. To contribute to this area of research, a machine learning model capable of accurately predicting nuclear power plant response with minimal computational cost is proposed. To develop a robust machine learning model, the Best Estimate Plus Uncertainty (BEPU) approach was used to generate a database to train three models and select the best of the three. The BEPU analysis was performed by coupling Dakota platform with the best estimate thermal hydraulics code RELAP/SCDAPSIM/MOD 3.4. The Code Scaling Applicability and Uncertainty approach was adopted, along with Wilks' theorem to obtain a statistically representative sample that satisfies the USNRC 95/95 rule with 95% probability and 95% confidence level. The generated database was used to train three models based on Recurrent Neural Networks; specifically, Long Short-Term Memory, Gated Recurrent Unit, and a hybrid model with Long Short-Term Memory coupled to Convolutional Neural Network. In this paper, the System Engineering approach was utilized to identify requirements, stakeholders, and functional and physical architecture to develop this project and ensure success in verification and validation activities necessary to ensure the efficient development of ML meta-models capable of predicting of the nuclear power plant response.

• 한국융합학회논문지
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• 제8권8호
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• pp.163-176
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• 2017

본 연구는 여성 갑상선 암환자의 불안, 우울, 불확실성, 사회적 지지와 삶의 질의 정도를 파악하고, 불안, 우울, 불확실성, 사회적 지지가 삶의 질에 미치는 영향을 파악하고자 수행되었다. 본 연구는 서술적 조사연구로 2014년 4월부터 10월까지 불안, 우울, 불확실성, 사회적지지, 삶의 질 측정도구를 이용하여 설문조사를 시행하였다. 연구대상자는 갑상선암을 진단 또는 치료받고 일 병원 내분비외과 외래를 방문중인 갑상선암 환자를 편의 표출하였으며, 자료수집이 완료된 106명의 자료를 SPSS 22.0을 이용하여 분석하였다. 연구결과 대상자의 삶의 질은 중간정도로 나타났으며, 불안은 신체기능과 정서기능, 사회기능에 유의하게 영향을 미치는 것으로 나타났고, 불확실성은 신체기능과 인지기능에 유의하게 영향을 미치는 것으로 나타났다. 본 연구결과를 통해 드러난 여성 갑상선암 환자들의 삶의 질 향상을 위해 불안과 불확실성을 감소시키기 위한 중재방안의 모색이 필요하다. 또한 후속 연구들에서는 보다 다양한 환경과 다양한 치료시기의 대상자를 표집하여 삶의 질에 대한 영향요인을 융복합적인 측면에서 파악할 필요가 있다.

• 한국전자파학회논문지
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• 제20권1호
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• pp.91-99
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• 2009

본 논문에서는 micro-TEM cell을 사용한 표준 전자기장 발생법을 기술하고 측정불확도를 평가하였다. 표준 전자기장 발생 시스템은 auto-leveling 기능을 가진 신호발생부, 최대 1.2 GHz까지 동작하는 micro-TEM cell, 서미스터 마운트를 사용한 전력측정부로 구성된다. 표준 전자기장 발생법의 타당성을 보이기 위해 $10\;MHz{\sim}1\;GHz$ 대역에서 전자기장의 세기 20 V/m에 대해 실시된 전자기장의 세기 국제비교(CCEM.RF-K20)의 참여 결과를 제시하였다.

• 한국광학회지
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• 제35권2호
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• pp.61-70
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• 2024

400 nm부터 1,600 nm까지의 파장 영역에서 단일모드 광섬유에 결합된 12개의 다이오드 레이저 광원를 기반으로 하는 레이저 복사출력계 교정시스템을 소개한다. 본 시스템은 복사출력 측정위치에서 레이저 출력요동을 최소화하였고 모든 광원에 대해 비슷한 빔 크기를 갖는다. 또한 감응도의 비균일도 및 비선형성을 최소화하기 위해 적분구 기준기를 사용하였다. 이 교정시스템의 최소 측정불확도는 대부분의 레이저 파장에서 1.1% (k=2)로 추정된다.

• 대기
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• 제25권1호
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• pp.1-18
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• 2015

The most objective way to overcome the limitation of numerical weather prediction model is to represent the uncertainty of prediction by introducing probabilistic forecast. The uncertainty of the numerical weather prediction system developed due to the parameterization of unresolved scale motions and the energy losses from the sub-scale physical processes. In this study, we focused on the growth of model errors. We performed ensemble forecast to represent model uncertainty. By employing the multi-physics scheme (PHYS) and the stochastic kinetic energy backscatter scheme (SKEBS) in simulating typhoon Rusa (2002), we assessed the performance level of the two schemes. The both schemes produced better results than the control run did in the ensemble mean forecast of the track. The results using PHYS improved by 28% and those based on SKEBS did by 7%. Both of the ensemble mean errors of the both schemes increased rapidly at the forecast time 84 hrs. The both ensemble spreads increased gradually during integration. The results based on SKEBS represented model errors very well during the forecast time of 96 hrs. After the period, it produced an under-dispersive pattern. The simulation based on PHYS overestimated the ensemble mean error during integration and represented the real situation well at the forecast time of 120 hrs. The displacement speed of the typhoon based on PHYS was closest to the best track, especially after landfall. In the sensitivity tests of the model uncertainty of SKEBS, ensemble mean forecast was sensitive to the physics parameterization. By adjusting the forcing parameter of SKEBS, the default experiment improved in the ensemble spread, ensemble mean errors, and moving speed.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2008년도 학술발표회 논문집
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• pp.299-303
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• 2008

In this study, an uncertainty assessment for surface air temperature(T2m) and precipitation(PCP) over East Asia is carried out. The data simulated by the intergovermental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) Atmosphere-Ocean coupled general circulation Model (AOGCM) are used to assess the uncertainty. Examination of the seasonal uncertainty of T2m and PCP variabilities shows that spring-summer cold bias and fall warm bias of T2m are found over both East Asia and the Korea peninsula. In contrast, distinctly summer dry bias and winter-spring wet bias of PCP over the Korea peninsula is found. To investigate the PCP seasonal variability over East Asia, the cyclostationary empirical orthogonal function(CSEOF) analysis is employed. The CSEOF analysis can extract physical modes (spatio-temporal patterns) and their undulation (PC time series) of PCP, showing the evolution of PCP. A comparison between spatio-temporal patterns of observed and modeled PCP anomalies shows that positive PCP anomalies located in northeastern China (north of Korea) of the multi-model ensemble(MME) cannot explain properly the contribution to summer monsoon rainfalls across Korea and Japan. The uncertainty of modeled PCP indicates that there is disagreement between observed and MME anomalies. The spatio-temporal deviation of the PCP is significantly associated with lower- and upper-level circulations. In particular, lower-level moisture transports from the warm pool of the western Pacific and corresponding moisture convergence significantly contribute to summer rainfalls. These lower- and upper-level circulations physically consistent with PCP give a insight of the reason why differences between modeled and observed PCP occur.

• 한국분무공학회지
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• 제5권4호
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• pp.12-32
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• 2000

The recent trends in numerical simulation of various spray phenomena are reviewed in this article. Major subtopics are atomization/breakup, collision/coalescence, wall collision, interfacial transfer, droplet dispersion, two-phase injection and spray combustion. Each submodel has been under continuous refinement and validation against more extensive data base by advanced laser diagnostic techniques. Most uncertainty in current spray simulations come from these physical submodels, not from excessive computational constraints.

• 한국가구학회지
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• 제11권1호
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• pp.75-84
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• 2000

Ginkgo trees have long been planted in Korea as roadside trees and ornamental trees, but the wood was seldom used except some utilization for small artifacts. Soaring prices of imported wood and future uncertainty about long-term supply of foreign woods have stimulated research on value-added utilization of less-utilized domestic wood resources such as Ginkgo wood. The properties of Ginkgo wood were investigated to determine its utilization potential in this study, and the results of anatomical, physical, and mechanical studies were presented with chemical compositions.

• International journal of advanced smart convergence
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• 제11권3호
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• pp.56-63
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• 2022

Cyber-physical systems (CPSs) can solve real problems by utilizing closely connected resources in the cyber world. Most problems arise because the physical world is uncertain and unpredictable. To address this uncertainty, information pouring from numerous devices must be collected in real-time, and each interconnected device must share the information. At this time, CPS must meet timing-related techniques and strict timing constraints that can deliver accurate information within predefined deadlines in order to interact closely beyond simply connecting the cyber and physical worlds. Timing errors in safety-critical systems, such as automobiles, aviation, and medical systems, can lead to catastrophic disasters. In this paper, we classify timing problems into two types: real-time delay and synchronization problems. The results of this study can be used in the entire process of CPS system design, implementation, operation, verification, and maintenance. As a result, it can contribute to securing the safety and reliability of CPS.

• 융합정보논문지
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• 제9권4호
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• pp.152-159
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• 2019

본 연구는 거래비용이론을 경험재 선택에 적용하여 경험재의 거래특성과 거래비용에 대해 살펴보는 것을 목적으로 하였다. 경험재의 특성을 반영하여 경험특유성, 거래불확실성, 개인불확실성을 제안하고 이 변수들이 거래비용에 주는 영향, 거래비용이 선택의도에 주는 영향을 가정하였다. 경험재 선택에 관한 207부의 데이터를 분석한 결과는 다음과 같다. 첫째, 경험특유성(장소특유성, 물리적장비특유성, 지식기술특유성, 시간특유성), 거래불확실성(제품불확실성, 과정불확실성), 개인불확실성(선호불확실성, 상황불확실성)은 거래비용에 모두 긍정적 영향을 주는 것으로 나타났다. 둘째, 거래비용(탐색비용, 비교비용, 검사비용, 협상비용, 주문과지불비용, 전달비용)은 해당 경험재의 선택의도에 부정적 영향을 주는 것으로 나타났다. 본 연구의 결과는 거래비용의 증가가 경험재의 선택 가능성을 줄일 수 있고, 거래비용을 감소시키기 위해 경험특유성과 거래불확실성, 개인불확실성의 전략적 고려가 필요함을 보여주고 있다. 또한 거래와 비용적 관점에서의 접근이 부족했던 경험재 연구를 보완함으로써 이론적인 기여를 하고 있다.