• Title/Summary/Keyword: 확률론적 평가

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부산지역 해수면 상승의 확률론적 전망

  • Lee, Jeonghoon;Lee, Okjeong;Cha, Wooyoung;Kim, Sadan
    • Proceedings of the Korea Water Resources Association Conference
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    • 2016.05a
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    • pp.212-212
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    • 2016
  • 해수면 상승의 예측에 대한 근본적인 불확실성은 전 지구적 해수면 상승에 대한 가속도와 상대적으로 해수면에 영향을 미치는 지역적인 요소와 연관되어 있다. 최근, 기후 모형을 포함하는 다양한 모형의 결과와 빙하 관측자료, 그리고 이들의 해수면에 대한 기여도는 해수면 상승이 가속화될 것이라는 사실을 나타내지만, 아직 조수 관측과 위성 자료들은 이와 관련된 근거를 발견하지 못하고 있다. 본 논문에서는 연안도시 계획 설계자들이 이러한 해수면 상승의 불확실성을 고려할 수 있도록 미래 해수면 상승의 확률론적 산정을 제공하기 위해 최근 해수면 상승 가속과 그 상승률에 대해 선택된 분포와 관측 해수면 자료의 합성을 제시한다. 결과는 프로젝트 취약성을 평가하기 위한 위험도 기반 관리체계의 기준으로서 사용 될 수 있다. 또한, 기후 영향에 의한 해수면의 동역학적 지질물리학의 이해도를 증진시킴으로써, 분포의 선택과 정확성, 그리고 해수면 상승 예측이 개선될 것이라고 기대 된다. 본 연구에서 제시된 방법론은 사례연구로 부산에 적용되어 설명되어 진다.

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Application of Probabilistic Health Risk Analysis in Life Cycle Assessment -Part I : A General Framework for Uncertainty and Variability Analysis of Health Risk in Life Cycle Assessment (전과정평가에 있어 확률론적 건강영향분석기법 적용 -Part I : 전과정평가에 있어 확률론적 위해도 분석기법 적용방안에 관한 연구)

  • Choi, Kwang-Soo;Park, Jae-Sung
    • Journal of Environmental Impact Assessment
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    • v.9 no.3
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    • pp.185-202
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    • 2000
  • Uncertainty and variability in Life Cycle Assessment(LCA) have been significant key issues in LCA methodology with techniques in other research area such as social and political science. Variability is understood as stemming from inherent variations in the real world, while uncertainty comes from inaccurate measurements, lack of data, model assumptions, etc. Related articles in this issues were reviewed for classification, distinguish and elaboration of probabilistic/stochastic health risk analysis application in LCA. Concept of focal zone, streamlining technique, scenario modelling and Monte Carlo/Latin Hypercube risk analysis were applied to the uncertainty/variability analysis of health risk in LCA. These results show that this general framework of multi-disciplinary methodology between probabilistic health risk assessment and LCA was of benefit to decision making process by suppling information about input/output data sensitivity, health effect priority and health risk distribution. There should be further research needs for case study using this methodology.

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Seismic Fragility Analysis of PSC Containment Building by Nonlinear Analysis (비선형 지진해석에 의한 PSC 격납건물의 지진취약도 분석)

  • Choi, In-Kil;Ahn, Seong-Moon;Choun, Young-Sun
    • Journal of the Earthquake Engineering Society of Korea
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    • v.10 no.1 s.47
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    • pp.63-74
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    • 2006
  • The seismic fragility analysis method has been used as a quantitative seismic safety evaluation method for the NPP(Nuclear Power Plant) structures and equipments. The seismic fragility analysis gives a realistic seismic capacity excluding the convertism included in the design stage. The conservatism is considered as the probabilistic parameters related to the response and capacity in the seismic fragility analysis. In this study, the displacement based seismic fragility analysis method was proposed based on the nonlinear dynamic analysis results. In this study, the seismic safety of the prestressed concrete containment building of KSNP(Korean Standard Nuclear Power Plant) was evaluated for the scenario earthquakes, neat-fault, far-fault, design earthquake and probability based scenario earthquake, which can be occurred in the NPP sites.

Evaluation of Chloride Diffusion Behavior and Analysis of Probabilistic Service Life in Long Term Aged GGBFS Concrete (장기 재령 GGBFS 콘크리트의 염화물 확산 거동 평가 및 확률론적 염해 내구수명 해석)

  • Yoon, Yong-Sik;Kim, Tae-Hoon;Kwon, Seung-Jun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.24 no.3
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    • pp.47-56
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    • 2020
  • In this study, three levels of W/B(Water to Binder) ratio (0.37, 0.42, 0.47) and substitution ratio of GGBFS (Ground Granulated Blast Furnace Slag) rate (0 %, 30 %, 50 %) were considered to perform RCPT (Rapid Chloride Diffusion Test) at the 1,095 aged day. Accelerated chloride diffusion coefficient and passed charge of each concrete mixture were assessed according to Tang's method and ASTM C 1202, and improving behaviors of durability performance with increasing aged days are analyzed based on the test results of previous aged days from the preceding study. As the age of concrete increases, the passed charge and diffusion coefficient have been significantly reduced, and especially the concrete specimens containing GGBFS showed a significantly more reduction than OPC(Ordinary Portland Cement) concrete specimen by latent hydraulic activity. In the case of OPC concrete's results of passed charge, at the 1,095 days, two of them were still in the "Moderate" class. So, if only OPC is used as the binder of concrete, the resistance performance for chloride attack is weak. In this study, the time-parameters (m) were derived based on the results of the accelerated chloride diffusion coefficient, and the deterministic and probabilistic analysis for service life were performed by assuming the design variable as a probability function. For probabilistic service life analysis, durability failure probabilities were calculated using Monte Carlo Simulation (MCS) to evaluate service life. The service life of probabilistic method were lower than that of deterministic method, since the target value of PDF (Probability of Durability Failure) was set very low at 10 %. If the target value of PDF suitable for the purpose of using structure can be set and proper variability can be considered for each design variable, it is believed that more economical durability design can be made.

Comparative Study on the Applicability of Point Estimate Methods in Combination with Numerical Analysis for the Probabilistic Reliability Assessment of Underground Structures (수치해석과 연계한 지하구조물의 확률론적 신뢰성 평가를 위한 점추정법의 적용성에 관한 비교 연구)

  • Park, Do-Hyun;Kim, Hyung-Mok;Ryu, Dong-Woo;Choi, Byung-Hee;Han, Kong-Chang
    • Tunnel and Underground Space
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    • v.22 no.2
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    • pp.86-92
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    • 2012
  • Point estimate method has a less accuracy than Monte Carlo simulation that is usually considered as an exact probabilistic method, but this method still remains popular in probability-based reliability assessment in geotechnical and rock engineering, because it significantly reduce the number of sampling points and produces the statistical moments of a performance function in a reasonable accuracy. In the present study, we investigated the accuracy and applicability of point estimate methods proposed by Rosenblueth and Zhou & Nowak by comparing the results of these two methods with those of Monte Carlo simulations. The comparison was carried out for the problem of a lined circular tunnel in an elastic medium where an closed-form analytical solution is given. The comparison results showed that despite the non-linearity of the analytical solution, the statistical moments calculated by the point estimate methods and the Monte Carlo simulations agreed well with an average error of roughly 1-2%. This average error demonstrates the applicability of the two point estimate methods for the probabilistic reliability assessment of underground structures in combination with numerical analysis.

Feasibility Study of Seismic Probabilistic Risk Assessment for Multi-unit NPP with Seismic Failure Correlation (다수기의 확률론적 지진안전성 평가를 위한 지진손상 상관계수의 적용)

  • Eem, Seunghyun;Kwag, Shinyoung;Choi, In-Kil
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.34 no.5
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    • pp.319-325
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    • 2021
  • The 2011 East Japan Earthquake caused accidents at a number of nuclear power plants in Fukushima, highlighting the need for a study on the seismic safety of multiple NPP (Nuclear Power Plant) units. In the case of nuclear power plants built on a site that shows a similar seismic response, there is at least a correlation between the seismic damage of structures, systems, and components (SSCs) of nuclear power plants. In this study, a probabilistic seismic safety assessment was performed for the loss of essential power events of twin units. To derive an appropriate seismic damage correlation coefficient, a probabilistic seismic response analysis was performed. Using the external event mensuration system program, we analyzed the seismic fragility and seismic risk by composing a failure tree of multiple loss of essential power events. Additionally, a comparative analysis was performed considering the seismic damage correlation between SSCs as completely independent and completely dependent.

Construction of Logic Trees and Hazard Curves for Probabilistic Tsunami Hazard Analysis (확률론적 지진해일 재해도평가를 위한 로직트리 작성 및 재해곡선 산출 방법)

  • Jho, Myeong Hwan;Kim, Gun Hyeong;Yoon, Sung Bum
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.31 no.2
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    • pp.62-72
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    • 2019
  • Due to the difficulties in forecasting the intensity and the source location of tsunami the countermeasures prepared based on the deterministic approach fail to work properly. Thus, there is an increasing demand of the tsunami hazard analyses that consider the uncertainties of tsunami behavior in probabilistic approach. In this paper a fundamental study is conducted to perform the probabilistic tsunami hazard analysis (PTHA) for the tsunamis that caused the disaster to the east coast of Korea. A logic tree approach is employed to consider the uncertainties of the initial free surface displacement and the tsunami height distribution along the coast. The branches of the logic tree are constructed by reflecting characteristics of tsunamis that have attacked the east coast of Korea. The computational time is nonlinearly increasing if the number of branches increases in the process of extracting the fractile curves. Thus, an improved method valid even for the case of a huge number of branches is proposed to save the computational time. The performance of the discrete weight distribution method proposed first in this study is compared with those of the conventional sorting method and the Monte Carlo method. The present method is comparable to the conventional methods in its accuracy, and is efficient in the sense of computational time when compared with the conventional sorting method. The Monte Carlo method, however, is more efficient than the other two methods if the number of branches and the number of fault segments increase significantly.

Human Health Risk Assessment of Polycyclic Aromatic Hydrocarbons (PAHs) from Road Dust Sediments in Korea (국내 도로 노면 퇴적입자 내 PAHs의 인체 위해성 평가)

  • Lee, Gain;Kim, Hongkyoung;Ji, Seungmin;Jang, Yong-Chul
    • Journal of Environmental Impact Assessment
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    • v.29 no.4
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    • pp.286-297
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    • 2020
  • This research studied human health risk assessment of PAHs (Polycyclic Aromatic Hydrocarbons) in road dust sediments collected from 6 sites in four different cities in Korea. PAHs are well known to be human carcinogens and toxic compounds that are commonly generated from incomplete combustion of fuels and energy products. Such compounds which is absorbed by atmospheric suspended dust can be emitted into air in gaseous form and often deposited on road dust sediments. The PAHs which is deposited on sediment particles can also be re-dispersed by vehicles or winds on the road surface. It can be harmful for humans when exposed via breathing, ingestion and dermal contact. This study examined human health risk assessment of PAHs in deposited road dust sediments. Results showed that the excess cancer risk estimates were above 1.0×10-6 at main traffic roads and resident area in Ulsan city. According to the result of deterministic risk assessment, dermal-contact was the major pathway, while the contribution of the risk from inhalation was less than 1%. The probabilistic risk assessment showed similar levels of cancer risk derived from the deterministic risk assessment. The result of sensitivity analysis reveal that exposure time is the most contributing factor (69%). Since the values of carcinogenic risk assessment were higher than 1.0 × 10-6, further detailed monitoring and refined risk assessment for PAHs may be required to identify more reliable and potential cancer risks for those who live in the study locations in Ulsan city.

Probabilistic Seepage Analysis Considering the Spatial Variability of Permeability for Layered Soil (투수계수의 공간적 변동성을 고려한 층상지반에 대한 확률론적 침투해석)

  • Cho, Sung-Eun
    • Journal of the Korean Geotechnical Society
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    • v.28 no.12
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    • pp.65-76
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    • 2012
  • In this study, probabilistic analysis of seepage through a two-layered soil foundation was performed. The hydraulic conductivity of soil shows significant spatial variations in different layers because of stratification; further, it varies on a smaller scale within each individual layer. Therefore, the deterministic seepage analysis method was extended to develop a probabilistic approach that accounts for the uncertainties and spatial variation of the hydraulic conductivity in a layered soil profile. Two-dimensional random fields were generated on the basis of the Karhunen-Lo$\grave{e}$ve expansion in a manner consistent with a specified marginal distribution function and an autocorrelation function for each layer. A Monte Carlo simulation was then used to determine the statistical response based on the random fields. A series of analyses were performed to verify the application potential of the proposed method and to study the effects of uncertainty due to the spatial heterogeneity on the seepage behavior of two-layered soil foundation beneath water retaining structure. The results showed that the probabilistic framework can be used to efficiently consider the various flow patterns caused by the spatial variability of the hydraulic conductivity in seepage assessment for a layered soil foundation.