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Widmanstatten 조직을 가지는 Ti-6Al-4V 합금의 준정적 및 동적 변형거동에 미치는 미세조직인자의 영향
李東根,李聖鶴,李鍾洙,許善茂 대한금속재료학회 2001 대한금속·재료학회지 Vol.39 No.12
This study is concerned with the effects of microstructural parameters on the quasi-static tensile and dynamic torsional deformation behaviors in Ti-6Al-4V alloys with Widmansta¨tten structures. Dynamic torsional tests were conducted using a torsional Kolsky bar for five Widmansta¨tten structures, which effective grain sizes such as colony size and α lamellar spacing were varied by heat-treatments, and then the test data were analyzed in relation to microstructures, tensile properties, and fracture mode. Under dynamic torsional loading, maximum shear stress showed a large dependence on the colony size as the effective grain size, while shear strain at the maximum shear stress point was largely affected by both the α lamellar spacing and the colony size. Adiabatic shear bands were found in the deformed region of the fractured specimens, and their width was smallest in the specimen having the large α lamellar spacing and colony size. The possibility of the adiabatic shear band formation was quantitatively analyzed by the theoretical critical shear strain (γ_c) condition. It was found to be most likely in the coarse Widmanstatten structure, whereas least likely in the fine Widmanstatten structure.
이동근,이유환,이성학,이종수,이충열,허선무 대한금속재료학회 2003 대한금속·재료학회지 Vol.41 No.10
The effects of microstructural morphology on dynamic deformation and fracture behavior and ballistic performance of a Ti-6Al-4V alloy were investigated in this study. Ballistic impact tests were conducted on equiaxed and bimodal microstructures, which were processed by different heat treatments, and then the test data were analyzed in relation to microstructures, tensile properties, and dynamic torsional test data. In the impacted region of the equiaxed microstructure, a number of adiabatic shear bands and cracks were observed to be formed along plastic flow lines, and delamination occurred because of cracking along the plastic flow lines or shear bands. In the case of the bimodal microstructure, shear bands were found in limited area near the impacted region without occurring delamination, and their number was fewer than that of the equiaxed microstructure. Thus, ballistic performance of the bimodal microstructure was better than that of the equiaxed microstructure. The ballistic performance of the two microstructures was also discussed by comparing the possibility of adiabatic shear band formation obtained from dynamic torsional test data.
Ti-6Al-4V 합금의 동적변형특성과 탄도충격성능 : 1. 초고속 폭발충격 특성 1. Ultra-high-speed Exploding Properties
이유환,이동근,이성학,이종수,최준홍,허선무 대한금속재료학회 2003 대한금속·재료학회지 Vol.41 No.10
The effects of microstructural morphology on ultra-high-speed exploding properties of Ti-6Al-4V alloy were investigated in this study. Exploding bridge wire (EBW) test was conducted on equiaxed and bimodal microstructures, which were processed by different heat treatments. From the test, moving velocity of free surface vs time profiles were obtained to measure strength at Hugoniot elastic limit (HEL) and spall strength and to subsequently predict ballistic mass efficiency. The EBW results indicated that impact resistance of the bimodal microstructure was better than that of the equiaxed microstructure when the measured strength at HEL and spall strength were considered. It was also learned from the observation of fractured EBW specimens that fracture occurred by the initiation and propagation of long cracks in the equiaxed microstructure, whereas a number of microcracks were formed and connected each other in a zig-zag pattern to reduce the driving force for crack propagation in the bimodal microstructure. Since the EBW test helped experimentally estimate ultra-high-speed deformation and fracture behavior, it could be effectively used for the prediction of ballistic impact performance.
Mivacurium 투여후 혈청 K^+치의 변동 및 근육통에 관한 연구
최세진,손수창,허동식 충남대학교 의과대학 지역사회의학연구소 1998 충남의대잡지 Vol.25 No.2
Hyperkalemia and muscle pain after succinylcholine induction of general anesthesia are disturbing and rarely fetal complications. Nondepolarising muscle relaxant mivacurium similar to depolarizing muscle relaxant succinylcholine with respect to rapid onset, short action time, and metabolized by plasma cholinesterase. Thus we think what happen after mivacurium induction, potassium, sodium and muscle pain, respectively. 18 patients are randomly choose and sampling before and 5, 10, 15 minutes after mivacurium induction and intubation of general anesthesia and analyzed. And we evaluated muscle pains after mivacurium induction of general anesthesia postoperatively.
Soo-Kwon Park,Woon-Ha Hwang,Dong-Jin Shin,Yeon-Jae Hur,Tae-Heon Kim,Sang-Ik Han,Jun-Hyun Cho,Jong-Hee Lee,Ji-Yoon Lee,Min-Hee Nam,Dong-Soo Park 한국육종학회 2014 한국육종학회 심포지엄 Vol.2014 No.07
Green rice leafhopper(GRH), Nephotettix cincticeps Uhier, is one of the major insect pests of rice (Oryza sativa L.) in the temperate growing region of East Asia. GRH sucks sap from both xylem and phoem of susceptible rice varieties, and increased GRH populations cause sooty mold disease on the ears of rice after heading stage. In addition to direct plant destruction, GRH also causes damage to rice plants by transmitting rice dwarf viruses causing rice dwarf viruses disease which could decrease the yield of rice. Development of GRH resistant rice varieties for reducing yield loss is an important objective in current breeding programs. In this study, we developed three SSR markers(RM18166, RM516, RM18171) and one Indel marker(Indel15040) which could select Grh1-resistant varieties using population derived from cross lines between Grh1-resistant variety ‘Singwang’ which contains Grh1 gene and susceptible variety ‘Ilpum’. PCR products of RM18166 which was one of the developed markers were easily detected in agarose gel. These markers will be useful for development of the Grh1-resistant varieties through marker-assisted selection(MAS) without bio-examination in rice breeding
Dong Won Seol,Soo Yeon Im,Woo June Hur,Min Ouk Park,Dong Soo Kim,Jae Yoon Jo,In Seok Park 한국유전학회 2008 Genes & Genomics Vol.30 No.3
Haematological features pertaining to aerobic capability were compared between diploid and triploid specimens of the Far Eastern catfish, Silurus asotus. No significant differences between diploids and triploids were found for the haematocrit value, total haemoglobin, and mean corpuscular haemoglobin concentration, while the mean corpuscular volume, mean corpuscular haemoglobin, and plasma glucose concentration were significantly higher in triploids than in diploids, and the number of red blood cells was significantly lower in triploids than in diploids. The oxygen consumption rate did not differ significantly between diploid and triploid fish ( P>0.05). Nevertheless, the respiratory frequency was higher in triploids than in diploids ( P< 0.05). Triploids were characterized by a lower concentration of circulating blood cells, and aquaculture practice should consider the need for a lower surface to volume ratio.
해저지반 상부에 설치된 침매터널에 작용하는 동수압에 관한 수치실험
허동수(Hur, Dong Soo),김창훈(Kim, Chang Hoon),염경선(Yeom, Gyeong Seon),김도삼(Kim, Do Sam) 한국해안해양공학회 2005 한국해안해양공학회 논문집 Vol.17 No.4
지금까지 침매터널에 대한 대부분의 연구들은 건설기술자의 경험에 바탕을 둔 연구들이었다. 공학적인 관점에서 파랑하중에 의한 침매터널의 안정성은 지반기초의 거동에 큰 영향을 받으므로 파·지반·침매터널의 상호작용에 대한 이해는 매우 중요하다. 본 연구에서는 파·지반·침매터널의 상호작용의 메커니즘에 대한 이해를 위하여 부산-거제간 연결도로 민간투자사업 구간 중 침매터널 구간에 직접수치해석기법을 적용하여 침매터널 주변의 지반 및 피복층 내에서 파랑하중에 의한 간극수압, 와도 및 흐름의 특성을 종합적으로 살펴보았다. 또한 다양한 파랑조건 및 피복층의 평균입경변화에 따른 비선형성의 파랑과 침매터널 및 지반의 상호작용이 침매터널의 안정성과 관련하여 논의되었다. Most immersed tunnels investigated have been investigated based on the engineer's experience with design and construction. From engineering point of view, it is very important to understand the wave interaction with the seabed and immersed tunnel, since the stability of an immersed tunnel depends largely on the behavior of the seabed foundation. In this study, for the first stage research to find out the mechanism of the wave interaction with the seabed and immersed tunnel, the benchmarking method called as direct numerical simulation (DNS) was employed to analyze comprehensively the wave-induced pore water pressures, vorticity and flows in seabed or inside rubble stone around the immersed tunnel. The immersed tunnel is modeled based on Busan-Geoje fixed link project in Korea, which is now on the stage of planning. Moreover, the nonlinear water wave interaction with an immersed tunnel/its seabed foundation was thoroughly examined with regard to the stabilities of the immersed tunnel subjected to various water wave conditions, median grain size and so forth.
허동수(Dong-Soo Hur),정영한(Yeong-Han Jeong),안성욱(Seong-wook An),박종배(Jong-Bae Park) 한국해양환경·에너지학회 2012 한국해양환경공학회 학술대회논문집 Vol.2012 No.5
The objective of this study is to analyze nonlinear wave-current interaction directly using LES-WASS-3D. The fully-nonlinear three-dimensional numerical model LES-WASS-3D is upgraded with the addition of salinity and temperature advection-diffusion equation. The numerical simulation was conducted with the consideration of wave in the estuary area with currents from river. Based on the results of the numerical simulation, the wave influence of salt water wedge and fresh water diffusion is discussed.