• Nuclear Engineering and Technology
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• 제52권4호
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• pp.755-763
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• 2020

The critical flow phenomenon has been studied because of its significant effect for design basis accidents in nuclear power plants. Transition points from thermal non-equilibrium to equilibrium are different according to the geometric effect on the critical flow. This study evaluates the uncertainty parameters of the critical flow model for analysis of DBA (Design Basis Accident) with the MARS-KS (Multi-dimensional Analysis for Reactor Safety-KINS Standard) code used as an independent regulatory assessment. The uncertainty of the critical flow model is represented by three parameters including the thermal non-equilibrium factor, discharge coefficient, and length to diameter (L/D) ratio, and their ranges are determined using large-scale Marviken test data. The uncertainty range of the thermal non-equilibrium factor is updated by the MCDA (Model Calibration through Data Assimilation) method. The updated uncertainty range is confirmed using an LBLOCA (Large Break Loss of Coolant Accident) experiment in the LOFT (Loss of Fluid Test) facility. The uncertainty ranges are also used to calculate an LBLOCA of the APR (Advanced Power Reactor) 1400 NPP (Nuclear Power Plants), focusing on the effect of the PCT (Peak Cladding Temperature). The results reveal that break flow is strongly dependent on the degree of the thermal non-equilibrium state in a ruptured pipe with a small L/D ratio. Moreover, this study provides the method to handle the thermal non-equilibrium factor, discharge coefficient, and length to diameter (L/D) ratio in the system code.

• 한국재난정보학회 논문집
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• 제17권2호
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• pp.226-235
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• 2021

연구목적: 에너지저장시설의 주요 시설물인 Coalescer 시설물을 대상으로 현행 설계기준(KBC2016)에 따라 지진에 대한 위험성평가를 수행하였다. 연구방법: 구조해석은 상용프로그램인 MIDAS-IT의 MIDAS GENw를 사용하였고, 구조물의 해석을 위해 기존 설계 도서를 준용하였으며, 해석에 사용한 하중은 국토교통부의 「건축구조기준 KBC2016」와 미국 연방기준인 「Provisions of the Uniform Building Code」를 따랐다. 연구결과: 본 연구에서는 지진하중을 정적으로 재하하고 특급 구조물의 붕괴방지수준에 대하여 평가함으로써 시설물의 관리자가 간편하게 위험도를 인지하고 평가할 수 있도록 고려하였으며, 본 해석결과를 활용하여 향후 시설물의 위험관리에 적용할 수 있도록 지진해석을 수행하였다. 결론: 현재 설계기준인 KBC2016에 의해 Coalescer 시설을 해석한 결과, 주요 지지부재의 stress ratio는 최대 4.7% 정도로 나타났다. 따라서 Coalescer를 지지하는 부재는 국내에 발생할 수 있는 재현주기 2400년 수준의 지진에 대하여 안전한 것으로 해석되었다.

• 한국산학기술학회논문지
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• 제20권3호
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• pp.602-608
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• 2019

본 연구에서는 강박스거더교 바닥판의 아스팔트 두께에 따른 단면 상하 온도차를 산정하고, 이에 따른 설계기준의 자료를 제공하고자 하였다. 아스팔트 두께 0mm, 50mm, 100m, 150mm의 4개 강박스거더 모형시험체를 제작하였다. 각 모형에 17~23개의 온도 센서를 상부 콘크리트와 강박스거더에 부착하였다. 이 센서 중 Euro code와 온도차를 비교 할 수 있는 6개의 온도 게이지를 선정하였다. 각 모형의 기준 대기온도에서 최대 온도와 최저 온도를 계산하고, 이를 바탕으로 온도차(경사)를 산정하여, 4개 각 모형에서 온도차 모델을 제시하였다. 0mm ~ 100mm 온도차 모델은 슬래브 최상단에서 Euro code의 온도차와 비교할 때 -0.9~-1.5도 더 낮은 온도차를 보였다. 전체적으로 측정된 온도차는 Euro code와 비교하여 5.45%~8.33%정도의 오차가 있음을 확인하였다. 산정된 온도와 평균온도의 차를 표준오차의 배수로 산정한 표준오차 계수는 최상단과 최하 단에서 평균 2.50 ~ 2.51배의 값으로 일정한 범위에서 산정되었다. 제시된 온도차 모델은 국내 교량 온도설계 온도차 기준 산정 시 기본 자료로 활용될 수 있을 것으로 판단된다.

• Earthquakes and Structures
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• 제3권5호
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• pp.719-747
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• 2012

In this paper a novel approach is proposed to address the problem of deriving non-stationary stochastic processes which are compatible in the mean sense with a given (target) response (uniform hazard) spectrum (UHS) as commonly desired in the aseismic structural design regulated by contemporary codes of practice. The appealing feature of the approach is that it is non-iterative and "one-step". This is accomplished by solving a standard over-determined minimization problem in conjunction with appropriate median peak factors. These factors are determined by a plethora of reported new Monte Carlo studies which on their own possess considerable stochastic dynamics merit. In the proposed approach, generation and treatment of samples of the processes individually on a deterministic basis is not required as is the case with the various "two-step" approaches found in the literature addressing the herein considered task. The applicability and usefulness of the approach is demonstrated by furnishing extensive numerical data associated with the elastic design UHS of the current European (EC8) and the Chinese (GB 50011) aseismic code provisions. Purposely, simple and thus attractive from a practical viewpoint, uniformly modulated processes assuming either the Kanai-Tajimi (K-T) or the Clough-Penzien (C-P) spectral form are employed. The Monte Carlo studies yield damping and duration dependent median peak factor spectra, given in a polynomial form, associated with the first passage problem for UHS compatible K-T and C-P uniformly modulated stochastic processes. Hopefully, the herein derived stochastic processes and median peak factor spectra can be used to facilitate the aseismic design of structures regulated by contemporary code provisions in a Monte Carlo simulation-based or stochastic dynamics-based context of analysis.

• Earthquakes and Structures
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• 제3권3_4호
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• pp.581-609
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• 2012

In this paper a novel non-iterative approach is proposed to address the problem of deriving non-stationary stochastic processes which are compatible in the mean sense with a given (target) response (uniform hazard) spectrum (UHS) as commonly desired in the aseismic structural design regulated by contemporary codes of practice. This is accomplished by solving a standard over-determined minimization problem in conjunction with appropriate median peak factors. These factors are determined by a plethora of reported new Monte Carlo studies which on their own possess considerable stochastic dynamics merit. In the proposed approach, generation and treatment of samples of the processes individually on a deterministic basis is not required as is the case with the various approaches found in the literature addressing the herein considered task. The applicability and usefulness of the approach is demonstrated by furnishing extensive numerical data associated with the elastic design UHS of the current European (EC8) and the Chinese (GB 50011) aseismic code provisions. Purposely, simple and thus attractive from a practical viewpoint, uniformly modulated processes assuming either the Kanai-Tajimi (K-T) or the Clough-Penzien (C-P) spectral form are employed. The Monte Carlo studies yield damping and duration dependent median peak factor spectra, given in a polynomial form, associated with the first passage problem for UHS compatible K-T and C-P uniformly modulated stochastic processes. Hopefully, the herein derived stochastic processes and median peak factor spectra can be used to facilitate the aseismic design of structures regulated by contemporary code provisions in a Monte Carlo simulation-based or stochastic dynamics-based context of analysis.

• Steel and Composite Structures
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• 제6권4호
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• pp.285-302
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• 2006

This paper describes the design and behaviour of cold-formed stainless steel slender circular hollow section columns. The columns were compressed between fixed ends at different column lengths. The investigation focused on large diameter-to-plate thickness (D/t) ratio ranged from 100 to 200. An accurate finite element model has been developed. The initial local and overall geometric imperfections have been included in the finite element model. The material nonlinearity of the cold-formed stainless steel sections was incorporated in the model. The column strengths, load-shortening curves as well as failure modes were predicted using the finite element model. The nonlinear finite element model was verified against test results. An extensive parametric study was carried out to study the effects of cross-section geometries on the strength and behaviour of stainless steel slender circular hollow section columns with large D/t ratio. The column strengths predicted from the parametric study were compared with the design strengths calculated using the American Specification, Australian/New Zealand Standard and European Code for cold-formed stainless steel structures. It is shown that the design strengths obtained using the Australian/New Zealand and European specifications are generally unconservative for the cold-formed stainless steel slender circular hollow section columns, while the American Specification is generally quite conservative. Therefore, design equation was proposed in this study.

• 한국BIM학회 논문집
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• 제12권3호
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• pp.30-38
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• 2022

Railway is compsed in various components, such as subgrade, track bed, sleeper, rail, and overhead line, on a linear space. Therefore, comprehensive work for various design standards and guidelines is required when designing a railway facility. For this reason, much time and effort are required to review the relevant design standards and guidelines. While, automatic legal check system for BIM models has been developed in the architectural engineering, it has not been developed in the railway engineering. This study reviews the korean design standard and the korean code for railway engineering, and suggests some rule items of logical information. Comparing the suggested rule items to the railway BIM library, items of logical information and additional attribute information are obtained. The analysis results of railway design standards and BIM library presented in this study would be utilized for defining rule-set items that is essential for development of the automatic legal check system for railway BIM models.

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 2008년도 추계학술논문발표회 논문집
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• pp.340-347
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• 2008

Recently the consideration for occupant's security has been raised as very important design element from the fire by building's large sized, higher storied, and its compounded. But the domestic laws regulated the predicative laws according to the technical standard which has no difference from the past domestic evacuation regulation. Therefore, regulation of escape code and developing technology for Korean conditions are needed to reduce victims during disaster by protecting occupant and guiding people to safe places.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.3166-3171
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• 2011

The design standard for the thickness of reinforced roadbed is divided into high-speed and conventional railroad because dynamic characteristics of train loadings differ depending on the train speed. Due to the national plan for increasing the train speed for both conventional and new railroad lines, it is necessary to examine the applicability of concrete tracks and feasibility of the train speed increase on the conventional lines with the current thickness of the reinforced roadbed. In this study, a real-scale test was performed to monitor the dynamic characteristics of the reinforced roadbed with a thickness of 20cm and the train speed of 200km/h, 300km/h, and 400km/h. The test results were then compared with the design code to investigate the applicability of the conventional reinforced roadbed when the trains operate with higher speed.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집E
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• pp.469-473
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• 2001

It is very important that piping system shall meet the optimum design requirement as predicted in designing system. If the piping system proved not to meet the requirement in commission it shall be redesigned and corrected till the required capacity is satisfied. which costs much expense. The objective of this study is to understand steady 3-dimensional flow phenomena in a process piping system numerically. 3-dimensional numerical simulations with standard $k-{\epsilon}$ model were carried out by using ALGOR code for three cases of Reynolds number. 2500, 3500 and 4500, based on inlet pipe diameter and three cases of inflow air temperature, $20^{\circ}C,\;50^{\circ}C$ and $100^{\circ}C$.