Ti-6Al-4V 합금의 동적변형특성과 탄도충격성능 : 2. 동적비틀림 특성과 탄도충격성능 2. Dynamic Torsional Properties and Ballistic Performance

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.

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.

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.

Haematological Parameters and Respiratory Function in Diploid and Triploid Far Eastern Catfish, Silurus asotus

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.

Development of molecular markers for selection of green rice leafhopper (Grh1)-resistant rice variety

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

Sand Suction Characteristics in the Rear Side of a Revetment Using DEM-WASS-2D

Hur, Dong Soo,Cho, Won Chul,Lee, Jung Lyul,Jeong, Yeon Myeong Coastal Education and Research Foundation 2019 Journal of coastal research Vol.91 No.special

3차원 무반사 수치파동수조에서 경사입사파의 조파기법 개발

허동수(Hur, Dong-Soo),이우동(Lee, Woo-Dong) 한국해안해양공학회 2011 한국해안해양공학회 논문집 Vol.23 No.6

본 연구에서는 3차원 수치파동수조에서 무반사 조파시스템을 이용한 경사입사파의 조파방법을 새롭게 제안하고, 계산된 수면변위 및 수평유속에 대한 수치결과와 Stokes파의 3차 근사이론값과의 비교 분석을 통하여 새로운 모델의 검증을 실시하였다. 그 결과 본 연구에서 제안한 경사입사파의 조파방법의 타당성과 유효성을 확인할 수 있었다. In this study, generation methods of oblique incident wave are newly proposed and examined using the fully non-linear numerical model with non-reflected wave generation system(LES-WASS-3D). In order to verify, free surface elevation and horizontal velocities are compared with 3^rd -order Stokes wave theory in 3-D oblique incident wave field. As a results, it is revealed that the numerical results by newly proposed technique are in good agreement with the theory.

슈퍼태풍 내습 시·부산 경남 연안역의 폭풍해일고

허동수(Hur, Dong-Soo),이현우(Lee, Hyeon-Woo),이우동(Lee, Woo-Dong),배기성(Bae, Ki-Sung) 한국해안해양공학회 2008 한국해안해양공학회 논문집 Vol.20 No.1

최근, 전 세계적으로 지구 온난화가 가속화됨에 따라 해수면의 온도가 상승함과 동시에 태풍의 강도도 커지고 있는 실정이다. 우리나라의 경우에도 태풍을 연구하는 많은 학자들이 머지않은 미래에 슈퍼태풍이 내습할 것으로 예측하고 있다. 따라서 본 연구에서는 태풍 Maemi의 시동경로에 미국을 강타한 허리케인 Katrina(미국 뉴올리언스, 2005)와 태풍 Durian(필리핀, 2006) 및 태풍 Vera(일본 이세만, 1959)의 태풍특성(중심기압, 최대풍속반경,이동속도 등)을 조합하여 수치시뮬레이션을 실시하였다. 그 결과, 부산 경남 연안역 대부분의 지점에서 Maemi의 경로에 Durian과 Vera를 진행시킨 경우, Maemi내습 시보다 약 1.5~2.0배 높은 폭풍해일고를, Katrina의 경우, 약 4.0배 이상의 높은 폭풍해일고를 나타내었다. 이상과 같은 최대폭풍해일고의 수치로서 슈퍼태풍의 위험성을 충분히 인지하여 최적의 방재시스템을 구축하는 것이 폭풍해일의 재해예방 및 최소화를 위하여 조속히 해결하여야 할 과제이다. Recently, the unusual climate change is happening from the global warming in the whole world, the Korean peninsula is also no exception. It is predicted by many researchers that, in the near future, the Super-Typhoon of overwhelming power will occur due to rising temperatures on the sea surface around the Korean peninsula. In this study, numerical simulation has been performed with the Super-Typhoons which combined route of Typhoon Maemi with typhoon conditons of Hurricane Katrina (New Oleans in U.S.A, 2005), Typhoon Durian (philippine, 2006) and Typhoon Vera (Ise Bay in Japan, 1959) at Busan and Gyeongnam coastal area which has been badly damaged due to storm surge every year. From the numerical results, it is revealed that the storm surge heights of the Super-Typhoons are higher than that of Maemi, specially the storm surge height in the case of Katrina is about 4 times larger. So, it can be pointed out that the construction of countermeasures against disasters are very important in order to prepare against an attack of the Super-Typhoons.

해역구조물을 통한 월파의 3차원 수치계산기법의 개발

허동수(Hur, Dong-Soo),김인철(Kim, In-Chul) 한국해안해양공학회 2006 한국해안해양공학회 논문집 Vol.18 No.4

소파호안과 같은 해역구조물을 통한 월파량 산정에 수치해석기법을 적용하기 위하여 투과성 구조물의 취급 및 쇄파현상의 재현이 가능한 수치해석기법을 발판으로 하여 쇄파발생으로 인한 기포의 유입과 호안 배후의 월파로 인한 물방울의 자유낙하 및 사면유하 등을 고려할 수 있는 기법을 추가한 새로운 3차원 수치해석기법을 제안하여, 기존의 수리모형실험과 비교함으로써 그 타당성을 검증하였다. 소파호안을 대상으로 Ursell 수(=L²H/h³)가 커질수록 3차원 계산에 의해 얻어지는 월파유량은 증가하였으며 실험결과와도 잘 일치하고 있는 것을 확인하였다. 또한, 월파량 산정에 2차원 및 3차원수치해석기법을 이용할 경우의 차이점에 관하여 논의하였다. In three dimensional wave field, a direct numerical simulation model, which is able to handle free-fall and slope-fall of a waterdrop due to overtopping, is proposed to evaluate the overtopping rate on the coastal structures like an absorbing revetment. A comparison between the numerical model and existing experimental results for overtopping rate was made to validate the proposed numerical model's accuracy, and showed fairly good agreement between them. It is confirmed in numerical and hydraulic(existing) model test that the overtopping quantity on a absorbing revetment becomes larger with an increase in Ursell number. Also, the overtopping rate estimated by 3-D numerical model is compared with it obtained by 2-D numerical model.