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중증 노인 외상에서 사망 예측을 위한 손상 점수 체계 간의 비교
류호완,안재윤,서강석,박정배,김종근,이미진,류현욱,김윤정,김창호,최재영,이동언,여인환,문성배,조연주,정한솔,조재완,정해원 대한응급의학회 2020 대한응급의학회지 Vol.31 No.6
Objective: This study compared the prognostic performance of the following five injury severity scores: the Geriatric Trauma Outcome Score (GTOS), the Injury Severity Score (ISS), the New Injury Severity Score (NISS), the Revised Trauma Score (RTS), and the Trauma and Injury Severity Score (TRISS) for in-hospital mortality in severe geriatric trauma patients. Methods: A retrospective, cross-sectional, observational study was conducted using a database of severe geriatric trauma patients (age ≥65 years and ISS ≥16) who presented to a single regional trauma center between November 2016 and October 2018. We compared the baseline characteristics between the survivor and mortality groups and the predictive ability of the five scoring systems. Results: A total of 402 patients were included in the analysis; the in-hospital mortality rate was 25.6% (n=103). The TRISS had the highest area under the curve of 0.953 (95% confidence interval [CI], 0.927-0.971); followed by RTS, 0.777 (95% CI, 0.733-0.817); NISS, 0.733 (95% CI, 0.687-0.776); ISS, 0.660 (95% CI, 0.612-0.707); and GTOS, 0.660 (95% CI, 0.611-0.706) in severe geriatric trauma. The TRISS also had the highest area under the curve of 0.961 (0.919- 0.985) among the injury severity scoring systems in polytrauma. The predictive ability of TRISS was significantly higher than the other four scores with respect to overall trauma and polytrauma (P<0.001). Conclusion: The TRISS showed the highest prognostic performance for predicting in-hospital mortality among all the injury severity scoring systems in severe geriatric trauma.
원주방향 표면 결함이 존재하는 배관에 가해지는 비틀림을 포함한 복합하중에 대한 한계하중식 제시
류호완(Ho-Wan Ryu),한재준(Jae-Jun Han),김윤재(Yun-Jae Kim) 대한기계학회 2015 大韓機械學會論文集A Vol.39 No.5
후쿠시마 원전 사고 이후로 원자력 발전 플랜트의 배관 시스템에 가해지는 비틀림 하중의 영향에 대한 연구가 여러 연구자들에 의해서 수행되었다. 발전 플랜트의 원주방향 균열을 포함한 배관은 정상운전 조건이나 갑자기 발생한 사고에 의해서 굽힘과 비틀림과 같은 하중을 받을 수 있다. ASME 코드에서는 균열 배관의 구조건전성 확보를 위해서 한계하중 기법을 사용해서 완전소성 파단에 대한 결함 평가를 제공한다. 최근 개정된 코드에 따르면, 복합하중은 막응력과 굽힘 응력만을 포함하고 있다. 실제로 운전 환경에서 비틀림 하중이 가해질 수 있음에도 불구하고, 비틀림 하중을 평가하는 방법론에 대해서는 언급하지 않았다. 본 논문에서는 한계하중 분석을 기반으로 원주방향 균열 존재하는 배관에 단순 굽힘과 단순 비틀림, 인장을 포함한 굽힘 비틀림 복합하중이 가해질 경우에 대한 유한요소해석 결과를 포함하고 있다. 전단면 완전항복 기준을 만족하는 한계하중 이론해를 제안하고 유한요소해석을 통해서 이를 검증하였다. Since the Fukushima nuclear accident, several researchers are extensively studying the effect of torsion on the piping systems In nuclear power plants. Piping installations in power plants with a circumferential crack can be operated under combined loading conditions such as bending and torsion. ASME Code provides flaw evaluations for fully plastic fractures using limit load criteria for the structural integrity of the cracked pipes. According to the recent version of Code, combined loadings are provided only for the membrane and bending. Even though actual operating conditions have torsion loading, the methodology for evaluating torsion load is not established. This paper provides the results of limit load analyses by using finite element models for circumferentially cracked pipes under pure bending, pure torsion, and combined bending and torsion with tension. Theoretical limit load solutions based on net-section fully plastic criteria are suggested and verified with the results of finite element analyses.
고밀도 폴리에틸렌 융착부에 대한 단기간 파손 평가법 개발
류호완(Ho-Wan Ryu),한재준(Jae-Jun Han),김윤재(Yun-Jae Kim),김종성(Jong-Sung Kim),김정현(Jeong-Hyeon Kim),장창희(Chang-Heui Jang) 대한기계학회 2015 大韓機械學會論文集A Vol.39 No.4
최근 미국에서는 가동기간이 오래된 원전 매설배관에서 부식 및 침식에 의해 삼중수소 누설로 지하수가 오염되는 사례가 급증하고 있다. 따라서, 현재 원전 안전등급 매설배관으로 사용되고 있는 금속재료의 배관을 대신해서 부식 및 침식 등의 열화 손상에 대한 저항성이 우수한 고밀도 폴리에틸렌(HDPE) 배관을 ASME Code Class 3 안전계통 배관으로 사용하기 위한 연구가 수행되고 있다. 본 연구에서는 발전소 가동 중 매설배관에 가해질 수 있는 하중과 온도 범위를 바탕으로 HDPE 배관 융착부에 대한 인장 시험과 저속균열성장 (SCG) 시험을 수행하였다. 시험 결과로 얻은 SCG 시험편의 파단면을 분석하여 HDPE 재료의 파손 기구를 파악하였다. 이를 바탕으로 3D 유한요소 해석을 이용하여 균열이 있는 HDPE 재료가 버틸 수 있는 한계하중에 대한 검증을 수행하였다. In the US, the number of cases of subterranean water contamination from tritium leaking through a damaged buried nuclear power plant pipe continues to increase, and the degradation of the buried metal piping is emerging as a major issue. A pipe blocked from corrosion and/or degradation can lead to loss of cooling capacity in safety-related piping resulting in critical issues related to the safety and integrity of nuclear power plant operation. The ASME Boiler and Pressure Vessel Codes Committee (BPVC) has recently approved Code Case N-755 that describes the requirements for the use of polyethylene (PE) pipe for the construction of Section III, Division 1 Class 3 buried piping systems for service water applications in nuclear power plants. This paper contains tensile and slow crack growth (SCG) test results for high-density polyethylene (HDPE) pipe welds under the environmental conditions of a nuclear power plant. Based on these tests, the fracture surface of the PENT specimen was analyzed, and the fracture mechanisms of each fracture area were determined. Finally, by using 3D finite element analysis, limit loads of HDPE related to premature failure were verified.
Failure assessment diagram analysis of high density polyethylene pipes
한재준,류호완,김윤재,김종성,오영진,박흥배 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.12
This paper presents an analysis of failure assessment diagram for PE4710 grade high density polyethylene pipes, which are recentlyconcerned to use in the nuclear industry. Available test data of tensile, single edge notched tension specimens and pressurised pipes aresummarised and suitably characterised for use in the failure assessment diagram in R6 procedure. Critical crack lengths and failure modefor the pressurised pipes and single edge notched tension specimens are determined under sustained load and compared with test results. Based on the concept of linear elastic fracture mechanics, a slow crack growth rate of PE4710 at 95oC is obtained excluding crack initiationtime. To consider the effect of temperature on slow crack growth rate, a shift method is introduced. Remaining life is calculatedagainst the crack margin and compared with the failure time.
표준 인장시험과 반복하중 C(T) 시험을 이용한 균열해석에서의 Chaboche 복합경화 모델 결정법
황진하,김훈태,류호완,김윤재,김진원,권형도 한국압력기기공학회 2019 한국압력기기공학회 논문집 Vol.15 No.2
Cracked component analysis is needed for structural integrity analysis under seismic loading. Under large amplitude cyclic loading conditions, the change in material properties can be complex, depending on the magnitude of plastic strain. Therefore the cracked component analysis under cyclic loading should consider appropriate cyclic hardening model. This study introduces a procedure for determining an appropriate cyclic hardening model for cracked component analysis. The test material was nuclear-grade TP316 stainless steel. The material cyclic hardening was simulated using the Chaboche combined hardening model. The kinematic hardening model was determined from standard tensile test to cover the high and wide strain range. The isotropic hardening model was determined by simulating C(T) test under cyclic loading using ABAQUS debonding analysis. The suitability of the material hardening model was verified by comparing load-displacement curves of cyclic C(T) tests under different load ratios.