Experimental Study on Dynamic Crack Growth at 3PB Ductile Steel Specimens

Cho, J. U. 公州大學校 工學硏究院 生産技術硏究所 2005 論文集 Vol.13 No.-

Dynamic crack propagation in ductile steel is investigated by means of impact loaded 3 point bending specimens. Results from experiments and numerical simulations are compared. The specimen has the size 320x75 mm with a thickness of 10 mm. A modified 3PB specimen design with reduced width at the ends has been developed to avoid the influence of the uncertain boundary conditions at the impact heads. One static and two dynamic experiments with impact velocities of 30.2 m/s and 45.2 m/s are carried out. High speed photography is used to obtain crack growth and crack tip opening displacement data. Direct measurement of the relative rotation of the two specimen halves is made using by Moire interference pattern. The fracture surfaces of shear lip are obtained for all three loading conditions. The experiments indicate no or only a slight influence of the loading rate on the crack propagation.

소아기에 발견된 거대수신증 1례

백홍규,조지현,김홍섭,박동철,유병연,박웅채,조형구 건국대학교 의과학연구소 1993 건국의과학학술지 Vol.3 No.-

Hydronephrosis, which is a common disorder of childhood, may be secondary to a number of abnormalities of the urinary tract. A kidney containing more than 1,000ml fluid in its collecting system is generally defined as giant hydronephrosis. The common clinical manifestations of giant hydronephrosis are abdominal distension and loin or abdominal pain. The patient seems to seek medical help late due to tolerable symptoms and particularly in the state of poor economic condition. We present a giant hydronephrosis of contents of 7,000ml associated with ureteropelvic junction stricture on a 8-year-old male. The final diagnosis was performed by exploration of abdomen and nephrectomy was done.

CORRELATION BETWEEN J-INTEGRAL AND CMOD IN IMPACT BEHAVIOR OF 3-POINT BEND SPECIMEN

한문식,J. U. CHO 한국자동차공학회 2006 International journal of automotive technology Vol.7 No.3

Numerical calculations are made in order to find a posible correlation between the J-integral and the crackmouth opening displacement (CMOD) in dynamic nonlinear fracture experiments of 3-point bend (3PB) specimens. Bothelastic-plastic and elastic-viscoplastic materials are considered at different impact velocities. The J-integral may be dynamic experiments.

실험계획법을 이용한 선박용 벨로우즈의 형상최적화에 관한 연구

김종필(J. P. Kim),김형준(H. J. Kim),김현수(H. S. Kim),조우석(U. S. Cho),제승봉(S. B. Jeo) 한국정밀공학회 2005 한국정밀공학회 학술발표대회 논문집 Vol.2005 No.10월

The mechanical properties of bellows, such as the extensibility and the strength can be changed depending on the shape. For the shipbuilding material, it is favorable that the fatigue life is long due to the elastic property and the reduction of thermal stress in piping system. Nowadays, the domestic production and design of bellows are based on the E.J.M.A Code. Therefore, the design standard is in need because of much errors and lack of detailed analysis. In this study, it is attempted to find out the optimal shape of U-type ship"s bellows that is applied to design of experiment using the finite element method. The effective factors, mountain height, length, thickness, and number of mountains and the length of joint are considered and the proper values are chosen for the simulation. The number of mountains are increased, the volume increases above the standard volume and the stress obviously increases. In addition, the effect of the thickness of bellows on the stress is very large. Both of the volume and stress are decreasing at a certain lower value region.

CORRELATION BETWEEN J-INTEGRAL AND CMOD IN IMPACT BEHAVIOR OF 3-POINT BEND SPECIMEN

Han, M.S.,Cho, J.U. The Korean Society of Automotive Engineers 2006 International journal of automotive technology Vol.7 No.3

Numerical calculations are made in order to find a possible correlation between the J-integral and the crack mouth opening displacement(CMOD) in dynamic nonlinear fracture experiments of 3-point bend(3PB) specimens. Both elastic-plastic and elastic-viscoplastic materials are considered at different impact velocities. The J-integral may be estimated from the crack mouth opening displacement which can be measured directly from photographs taken during dynamic experiments.

CORRELATION BETWEEN J-INTEGRAL AND CMOD IN IMPACT BEHAVIOR OF 3-POINT BEND SPECIMEN

M. S. HAN,J. U. CHO 한국자동차공학회 2006 International journal of automotive technology Vol.7 No.3

Numerical calculations are made in order to find a possible correlation between the J-integral and the crack mouth opening displacement (CMOD) in dynamic nonlinear fracture experiments of 3-point bend (3PB) specimens. Both elastic-plastic and elastic-viscoplastic materials are considered at different impact velocities. The J-integral may be estimated from the crack mouth opening displacement which can be measured directly from photographs taken during dynamic experiments.

百日咳菌의 生物學的 活性에 관한 硏究 : 百日咳백신의 마우스 防禦力과 Histamine-Sensitizing Activity에 관하여 Histamine-Sensitizing and Protective Activity of Pertussis Vacaine in Mice

趙敏基,朴京錫,車應熙,金丁圭 國立保健硏究院 1975 국립보건연구원보 Vol.12 No.-

水稻의 亞黃酸가스 煙害에 관한 硏究 (Ⅰ) : 被害水稻의 營養學的實態와 品種抵抗性 Survey of nutritional status of suffered rice plant and varietal resistance

曺鍾澤,裵泰雄,韓熙世,河祥永,文炳周,金正基,孫賢秀 동아대학교 환경문제연구소 1978 硏究報告 Vol.2 No.1

Absorption of sulfur dioxide by rice plant of 10 varieties and its relation to the varietal resistance and nutrient contents of leaves in accordance with the increased sulfur contents were studied on rice plants in Ulsan district suffered from smoke injury as compared with those in Jinju district being not suffered. 1. The typical symptoms of SO₂ gas injury showing the smoky spots were presented on suffered leaves of rice plant in Ulsan district, however no symptoms were appeared in Jinju. 2. Soluble sulfur contents of leaves in affected rice plant in Ulsan were generally high, presenting the amount of 0.176%. 3. Average nitrogen content of suffered leaves in Ulsan was 1.68%, and showed statistically high correlation with soluble sulfur content. The correlation coefficient(r) was +0.557. 4. Negative correlation were revealed between S and Ca, K and P contents of leaves, having the coefficient of -0.354, -0.378, -0.27 respectively, and no significant correlation was found. 5. Mn, Mg and SiO₂ contents of leaves were showed no connection with S content of leaves. 6. The ratio of SiO₂/N and K₂O/N of leaves were highly correlated with S content having the coefficient of -0.535, -0.512 respectively. The ratio of K₂O/SiO₂ and CaO/MgO were not significantly correlated with S content. 7. Of the rice yield components, weight of unpolished rice per 10a, weight of unhulled rice 「per 10a, mating ratio, number of grain per panicle, 「panicle length and clum length of affected rice plant in Ulsan district were remarkedly reduced as compared with healthy rice plant in Jinju. 8. Weight of unpolished rice, number of grain per panicle and number of panicle, of the yield components for suffered rice plant in Ulsan district were revealed high amount in "Nopoong" variety and in "Milyang 23", the next.

부산지역 대기중 중금속 오염도

조현용,문덕환,전진호,이채언,김성천 인제대학교 1992 仁濟醫學 Vol.13 No.2

부산지역 대기중 총부유분진과 이에 함유된 중금속의 오염도를 파악하여 대기오염 저감대책 수립의 기초자료로 이용하고자 한다. This study was conducted for the purpose of proposing the basic data for establishing the control program of air pollution and contributing to health improvement and prevent disease of the residents in Pusan area by assessing the atmospheric level of total suspend particles TSP and heavy metals. The author measured the concentration of the Pb, Cd, Cr, V and Mn in the ambient air at the locations by measuring time (morning and afternoon) from January to March 1990 with the graphite furnace atomic absorption spectrophotometer. The locations selected were Sasang, Sinpyung, Jangrim and Daeshin-dong, Namchun-dong, haeunde, Yongdusan, which have been known as industrial cumplex area, residental area and park area, respectively, in Pusan. The results were as follows ; 1.The average concentration of TSP : 235.60±145.47㎍/㎥ 2.The average concentration of Pb : 1.31±0.38㎍/㎥ 3.The average concentration of Cd : 0.08±0.02㎍/㎥ 4.The average concentration of Cr : 1.06±0.23㎍/㎥ 5.The average concentration of V : 008±0.02㎍/㎥ 6.The average concentration of Mn : 3.90±1.14㎍/㎥ 7.The average concentration of heavy metals by area was the highest at industrial complex area, and the lovest at residental area. 8.The average concentration of TSP by area was the highest at industrial complex area, and the lovest at park area. 9.The average concentration of heavy metals during the day was relatively higher in the morning than in the afternoon

돼지 대장에서 분리한 E.coli의 중금속 내성에 관한 연구

조창현,정욱진,이영수,최인실,강희옥,박남규,김명화,변미경,이현숙 경상대학교 환경보전연구소 1993 環境保全硏究所報 Vol.1 No.1

돼지의 대장에서 서식하는 466개의 대장균 균주들을 분리하여, 중금속인 Ag, Cd, Cu, Hg, Ni 및Pb에 대한 저항성을 조사 하였다. 거의 대부분의 균주들이 이들 여섯가지 중금속 모두에 강한 저항성을 보였다. 이것은 우리 주위환경의 중금속 오염 정도가 심각하다는 것을 간접적으로 나타내는 것이다. Ag, Pb 및 Hg를 함유하고 있는 고체 배지에서 균주를 성장시켰을때, colony 색깔이 중금속 자체의 광택과 같은 색깔을 나타내는 점으로 보아, 이들 중금속에 대한 저항기작은 유해한 중금속 이온을 세포내 에서 무해한 금속 형태로 전환시켜 세포내에 축적시키는 기작임을 시사하였다. 그 중 가장 높은 저항성을 나타내는 isolate 385를 Ag와 Pb를 함유한 액체배지에서 각각 배양한 뒤 세포내 Ag와 Pb 축적량을 조사한 결과, 건조세포 무게당 0.72g Ag 및 0.23g Pb를 세포내에 축적하고 있었다. 따라서, 이 균주를 유전자 조작 등의 방법으로 개발 한다면 산업 폐수내에 존재하는 이 중금속들의 제거에 효율적으로 사용할 수 있을 것이라 사료된다. We isolated E.coli from porcine intestines and examined the resistances to various heavy-metals, Ag, Cd, Cu, Hg, Ni, and Pb. The 466 isolates were resistant to the heavy-metals. Among them, 72.1% was survived in 1 mM AgNO₃, 9.3% in 80 mM AgNO₃, 95.9% in 0.6 mM Cd(NO₃)₂, 5.6% in 3 mN Cd(NO₃)₂. 95.9% in Cu(NO₃)₂, 48.5% in 0.2 mM HgCl₂, 3.4% in 0.6 mM HgCl₂, 64.4% in 5 mM NiCl₂ and 67.4% in 10 mM Pb(NO₃)₂. The isolate 385 was most resistant to silver and lead ions and the MICs of the ions were 80 mM and 11 mM, respectively. These resistances were inducible by Ag^+ and Pb^2+ ions. When isolate 385 grew in LB-agar plates containing AgNO₃ or Pb(NO₃)₂, the colony colors were changed from light yellow to deep brown. This change to brown color suggests that the resistances of 385 cells to Ag^+ and Pb^2+ ions were due to the reducing mechanism which converted them into the elementary metals(Ag^0, Pb^0) after the uptake of the ions into the cells. The resistant cells accumulated 0.72gr of Ag^0 and 0.23gr of Pb^0 per cells dry wt.