http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
개선된 자동차용 강판 동적인장물성 측정에서의 표준불확도평가
최민국(Min Kuk Choi),정세환(Sehwan Jeong),허훈(Hoon Huh),김창근(Chang Geun Kim),채균식(Kyun Shik Chae) 한국자동차공학회 2013 한국자동차공학회 부문종합 학술대회 Vol.2013 No.5
Evaluation of the crashworthiness is one of the important issues in the automotive industry. In order to evaluate the crashworthiness of auto-body structure, finite element methods has been conducted for crash analysis. Generally, strain rates distribution of auto-body structure in the car crash is ranging from 0.001/s to 500/s. Since the material properties of steel sheets depend on the strain rates, the dynamic behavior of sheet metals must be examined and applied to the finite element model appropriately. This paper is concerned with the evaluation of standard uncertainty of modified measurement of high speed tensile properties of auto-body steel sheets. Obtaining procedure of the true stress?true strain data at intermediate strain rates is properly designed for the experiment and data acquisition compared with previous procedure. Standard uncertainty of the true stress is evaluated considering sources of uncertainties of input quantities and their associated sensitivity coefficients. A combined standard uncertainty is evaluated from not only the uncertainties of the input quantities but also the influence factor for the true stress. The results show that the standard uncertainty evaluation procedure has been successfully applied to high speed tensile properties.
소방안전관리자의 화재 대응력 향상을 위한 XR기반 화재 대응 시나리오 개발
최민국(Min Guk Choe),최유정(Yoo Jeong Choi),최수길(Su Gil Choi),김시국(Si Kuk Kim) 한국화재소방학회 2021 한국화재소방학회 학술대회 논문집 Vol.2021 No.추계
현대 건축물은 대형화, 고층화, 밀집화에 의하여 재해 발생의 형태가 다양⋅복잡하게 나타나고 있다. 최근에 발생한 화재사례로는 이천 쿠팡 물류센터 화재, 제천 스포츠센터 화재, 용인 SLC 물류센터 화재 등이 있으며, 해당 사례들의 공통점은 화재안전관리의 소홀함으로 인해 피해가 확대된 것이다. 이러한 사례를 통해 화재를 예방하기 위한 노력도 중요하지만, 화재로부터 피해를 최소화하기 위한 대처 또한 중요한 것을 확인할 수 있다. 소방안전관리자는 소방대가 도착하기 전까지 화재 사실을 인지하여 건물 내 재실자에게 화재를 경보하고, 화재로부터 재실자들을 대피시켜 화재 진압을 시도하거나, 연기나 화염으로 인해 피해가 확산하는 것을 막는 등 매우 중요한 역할을 맡고 있다. 하지만 대다수의 소방안전관리자는 화재경험이 전무하며, 특히, 많은 사람이 이용하는 다중이용시설이나 신속한 대피가 어려운 노유자시설과 같은 곳에서 근무하는 소방안전관리자의 경우 실질적인 교육을 통해 화재발생 시 취해야 할 행동과 침착한 대응이 어려운 실정이다. 이를 보완하기 위해 다양한 상황에 대한 훈련이 필요하지만, 현재의 교육 훈련으로는 분명한 한계가 있다. 이를 극복하는 방안으로 XR기기를 활용한 시뮬레이션 교육방법이 필요하며, XR기기를 활용한 특정 건축물에 대해 시나리오 훈련 방법을 통해 화재 발생 시 대피 시간을 가늠하고, 화재 상황에 능동적 상황판단 훈련이 필요하다. 본 연구에서는 실제 화재 시 발생이 가능한 상황별 훈련 시나리오를 개발하고자 한다. 개발한 시나리오는 국내에서 발생한 화재사고사례 분석을 통해 소방시설의 유지관리 실패로 인한 피해확대 요소를 적용하여 시나리오를 개발하였으며, 해당 시나리오를 통해 실제 상황과 유사한 콘텐츠 구현 및 반복적인 교육⋅훈련을 통한 현장에서의 빠른 판단과 대처 능력이 향상될 것으로 판단된다.
중 변형률속도 영역에서 차체 강판의 인장/압축 경화 거동에 관한 연구
주근수(Guensu Joo),최민국(Min Kuk Choi),허훈(Hoon Huh) 한국자동차공학회 2014 한국자동차공학회 부문종합 학술대회 Vol.2014 No.5
The tension/compression hardening behavior is important in sheet metal forming processes because of complicated loading paths. Experimental methods to measure the tension/ compression behavior have not considered the effect of the strain rate although the strain rate is related to the hardening behavior of sheet metal. The tension/compression tests need to be conducted considering the strain rate to acquire accurate hardening behavior. This paper deals with an experimental technique to measure the tension/compression behavior of sheet metal at strain rates from 0.001 s<SUP>-1</SUP> to 50 s<SUP>-1</SUP> for real sheet metal forming. A new clamping device was developed to prevent a sheet specimen from buckling under compression loading condition. Jig systems to impose pre-strain and reverse loading were also developed for high speed material testing machine. Tension/compression tests have been conducted at various strain rates for SPCC and DP590 with pre-strain of 10%. Hardening behavior under the tension or compression loading condition was compared to each other at severe strain rates.
정세환(Sehwan Jeong),허훈(Hoon Huh),최민국(Min Kuk Choi),채균식(Kyun Shik Chae),김창근(Chang-Geun Kim) 한국자동차공학회 2011 한국자동차공학회 학술대회 및 전시회 Vol.2011 No.11
This research is concerned with the standard uncertainties in the tensile properties of auto-body steel considering strain rate effects and effects of uncertainties of tensile properties on crash analyses. A procedure to obtain plastic true stress data and analytic uncertainty model are established. Uncertainty sources in the high-speed tensile test are summarized. Standard uncertainties in measuring input quantities such as load, length, thickness, and width of the specimens are calculated, as are their associated sensitivity coefficients. Uncertainty induced by the FFT smoothing process used to reduce unnecessary signal in acquired data is also considered. Image analysis using a high-speed camera is performed in order to measure the length of the specimen during the high-speed tensile test. Combined standard uncertainty is then evaluated for the true stress data of an auto-body steel sheet at intermediate strain rates. Crash analysis of a square tube is performed with measured true stress data considering standard uncertainties. In the analyses, maximum and minimum values of true stress data in the range of expanded uncertainty are applied into the analyses. Finally, effects of the uncertainties on the crash analyses are quantitatively evaluated.
허훈(Hoon Huh),송정한(Jung-Han Song),정세환(Sehwan Jeong),하지웅(Jiwoong Ha),임성준(Sung Jun Lim),최민국(Min Kuk Choi) 한국자동차공학회 2013 한국자동차공학회 학술대회 및 전시회 Vol.2013 No.11
The formability and crash worthiness of auto-body structures have been an important issue in the automotive industry because of the safety of passengers and usage of AHSS. This paper explains about the high speed mechanical property, failure load of welding and fracture model at a wide range of strain rate from 0.001/s to 200/s. Those properties and model can be directly applied to finite element analysis to evaluate the formability and the crashworthiness of auto-body structures. This paper introduces the acquisition procedure of the high speed tensile properties of auto-body steel sheets and the evaluation procedure of the standard uncertainty of the tensile properties as well as the effects of strain rate on the fracture locus and the failure load of spot and laser welding of auto-body steel sheets. Since a fracture model is indispensible for accurate assessment of the crashworthiness of an auto-body, a fracture model newly reported is also explained with derivation and application