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Amorphous Phase Formation in a Ni-Zr-Al-Y Alloy System
Kim, W.B.,Ye, B.J.,Yi, S. 대한금속재료학회 2004 METALS AND MATERIALS International Vol.10 No.1
Quaternary Ni-based amorphous alloys containing only metallic elements were developed through systematic alloy design. The importance of the phase equilibria information for the development of amorphous alloys was demonstrated through experimental results. Ni-Zr-Al ternary alloys having low liquidus temperature tend to have high GFA. Partial replacements of Zr with Y in the temary alloys significantly enhanced the GFA of the quaternary alloys. The alloy Ni_(60)Zr_(25)Al_(8)Y_(7) could be cast into a fully amorphous rod through an injection casting method. Since most Mi-based amorphous alloys reported to date contain non-metallic elements, the Ni-based amorphous alloys developed in the alloy system Ni-Zr-Al-Y are of interest.
SIZE OPTIMIATION OF AN ENGINE ROOM MEMBER FOR CRASHWORTHINESS USING RESPONSE SURFACE METHOD
S. OH,B.-W. YE,H.-C. SIN 한국자동차공학회 2007 International journal of automotive technology Vol.8 No.1
The frontal crash optimization of an engine room member using the response surface method was studied. The engine room member is composed of the front side member and the sub-frame. The thicknesses of the panels on the front side member and the sub-frame were selected as the design variables. The purpose of the optimization was to reduce the weight of the structure, under the constraint that the objective quantity of crash energy is absorbed. The response surface method was used to approximate the crash behavior in mathematical form for optimization procedure. To research the effect of the regression method, two different methodologies were used in constructing the response surface model, the least square method and the moving least square method. The optimum with the two methods was verified by the simulation result. The precision of the surrogate model affected the optimal design. The moving least square method showed better approximation than the least square method. In addition to the deterministic optimization, the reliabilitybased design optimization using the response surface method was executed to examine the effect of uncertainties in design variables. The requirement for reliability made the optimal structure be heavier than the result of the deterministic optimization. Compared with the deterministic optimum, the optimal design using the reliability-based design optimization showed higher crash energy absorption and little probability of failure in achieving the objective.
Effects of Excess Copper on Germination and Growth of Maize Plants
Shin, Ji Su(신지수),Kyo Sung Lee(이교석),Dong Sung Lee(이동성),Dae Sung Jeon(전대성),Youn K Lee(이연경),Misuk Park(박미숙),Ji W. Goo(구지원),Soo B. Kim(김수빈),Na Won Park(박나원),Ye Jin Park(박예진),So Jeong Kim(김소정),Bo Koung Lee 한국토양비료학회 2014 한국토양비료학회 학술발표회 초록집 Vol.2014 No.10
NUMERICAL SIMULATION OF CONVEX AND CONCAVE TUBES WITH CONSIDERATION OF STRAIN RATE SENSITIVITY
Ye, B.W.,Oh, S.,Cho, Y.B.,Sin, H.C. The Korean Society of Automotive Engineers 2007 International journal of automotive technology Vol.8 No.2
The present paper deals with the application of the explicit finite element code, PAM-CRASH, to simulate the crash behavior of steel thin-walled tubes with various cross-sections subjected to axial loading. An isotropic elastic, linear strain-hardening material model was used in the finite element analysis and the strain-rate sensitivity of mild steel was modeled by using the Cowper-Symonds constitutive equation with modified coefficients. The modified coefficients were applied in numerical collapse simulations of 11 types of thin-walled polygon tubes: 7 convex polygon tubes and 4 concave polygon tubes. The results show that the thin hexagonal tube and the thick octagonal tube showed relatively good performance within the convex polygon tubes. The crush strengths of the hexagonal and octagonal tubes increased by about 20% and 25% from the crush strength of the square tube, respectively. Among the concave tubes, the I-type tube showed the best performance. Its crush strength was about 50% higher than the crush strength of the square tube.
NUMERICAL SIMULATION OF CONVEX AND CONCAVE TUBES WITH CONSIDERATION OF STRAIN RATE SENSITIVITY
B.-W. YE,S. OH,Y.-B. CHO,H.-C. SIN 한국자동차공학회 2007 International journal of automotive technology Vol.8 No.2
The present paper deals with the application of the explicit finite element code, PAM-CRASH, to simulate the crash behavior of steel thin-walled tubes with various cross-sections subjected to axial loading. An isotropic elastic, linear strain-hardening material model was used in the finite element analysis and the strain-rate sensitivity of mild steel was modeled by using the Cowper-Symonds constitutive equation with modified coefficients. The modified coefficients were applied in numerical collapse simulations of 11 types of thin-walled polygon tubes: 7 convex polygon tubes and 4 concave polygon tubes. The results show that the thin hexagonal tube and the thick octagonal tube showed relatively good performance within the convex polygon tubes. The crush strengths of the hexagonal and octagonal tubes increased by about 20% and 25% from the crush strength of the square tube, respectively. Among the concave tubes, the I-type tube showed the best performance. Its crush strength was about 50% higher than the crush strength of the square tube.