• 제목/요약/키워드: Acquired resistance

검색결과 295건 처리시간 0.027초

AE에 의한 치과용 다이아몬드 버의 연삭가공 특성 (Grinding Characteristics of Diamond Burs in Dentistry)

  • 이근상;임영호;권동호;소의열
    • 한국생산제조학회지
    • /
    • 제8권3호
    • /
    • pp.76-82
    • /
    • 1999
  • This study was carried out to verify finding performance of dental diamond bur and investigate the possibility of AE application in density field. Work pieces were made of acryl and bovine respectively for the experiments in this study. Grinding test was conducted to get the data of grinding resistance and specific finding energy of low different types of diamond bur by using tool dynamometer. AE signal was acquired to verify grinding process in the AE measuring system. AErms value was increased as the grinding velocity and depth were increasing, but it decreased as the feed rate was increasing. The case of the small value of AE signal is due to abnormal grinding in D type diamond bur. By analyzing AErms start and finish time of grinding working, abnormal grinding state can be confined. Abnormal state can be found through the behavior of AE signal in the finding working. As a result, it is expected that forecast of abnormal state is possible using AE equipments under real time process.

  • PDF

Testing and finite element modeling of stressed skin diaphragms

  • Liu, Yang;Zhang, Qilin;Qian, Weijun
    • Steel and Composite Structures
    • /
    • 제7권1호
    • /
    • pp.35-52
    • /
    • 2007
  • The cold formed light-gauge profiled steel sheeting can offer considerable shear resistance acting in the steel building frame. This paper conducted the full-scale test on the shear behavior of stressed skin diaphragm using profiled sheeting connected by the self-tapping screws. A three-dimensional finite element model that simulates the stressed skin diaphragm was developed. The sheet was modeled using thin element model while the supporting members were simulated using beam elements. Fasteners were represented in the numerical model as equivalent springs. A joint test program was conducted to characterize the properties of these springs and results were reported in this study. Finite element model of the full-scale test was analyzed by use of the ANSYS package, considering nonlinearity caused by the large deflection and slip of fasteners. The experimental data was compared with the results acquired by the EUR formulas and finite element analysis.

고로슬래그미분말 및 플라이애쉬를 사용한 고유동콘크리트의 특성에 관한 연구 (Properties of Self-Compacting Concrete Using Ground Granulated Blast Furnace Slag and Fly ash)

  • 김은겸;박천세;최재진;전찬기;이호석
    • 한국콘크리트학회:학술대회논문집
    • /
    • 한국콘크리트학회 2003년도 봄 학술발표회 논문집
    • /
    • pp.89-94
    • /
    • 2003
  • In this research, the physical properties of self compacting concrete using ground granulated blast furnace slag and fly ash as a part of cement were investigated. Concrete using ground granulated blast furnace slag and fly ash was prepared with various ground granulated blast furnace slag(30-50 volume %) and fly ash(10-20 volume %) replacement for cement. The effect of each of the materals, which have effects on self compacting concrete made by the basic mix proportion used granulated blast furnace slag and fly ash after hardening, has been checked. The workability, flowing characteristics, resistance of segregation of materals, air content, and compressive strength of concrete using ground granulated blast furnace slag and fly ash were tested and the results were compared with those of ordinary portland cement concrete. In the experiment, we acquired satisfactory results at the point of flowing characteristics and strengths of concrete using ground granulated blast furnace and slag fly ash within the replacement ratio of 65%

  • PDF

세균성 폐렴과 항생제 선택 (Antibiotics for bacterial pneumonia in children)

  • 염혜영
    • Clinical and Experimental Pediatrics
    • /
    • 제52권3호
    • /
    • pp.283-288
    • /
    • 2009
  • Pneumonia remains the leading cause of mortality in children. Diagnosis depends on a combination of factors, including clinical assessment, radiological and laboratory findings. Although Streptococcus pneumoniae remains the most important cause of childhood bacterial pneumonia, the great majority of cases of community-acquired pneumonia (CAP) are of viral etiology. A new, rapid, and inexpensive test that differentiates viral from bacterial pneumonia is needed to decide empiric antibiotic treatment. Antibiotics effective against the expected bacterial pathogens should be instituted where necessary. The role of emerging pathogens and the effect of pneumococcal resistance and heptavalent conjugate pneumococcal vaccines are to be considered in practice. There are reports supporting the valid and highly efficacious use of penicillin as a first-line drug for treating CAP. This review raises the issue of the overuse of unnecessary antibiotics in viral CAPs and the use of second or third-line antibiotics for non-complicated pneumonias in most clinical settings.

알루미늄 2519 판재의 충격저항성 평가에 대한 수치 해석적 연구 (A Numerical Study on the Shock Resistance Test of Aluminium 2519 Plate)

  • 구만회;우호길
    • 한국군사과학기술학회지
    • /
    • 제7권3호
    • /
    • pp.11-20
    • /
    • 2004
  • In this paper, the acceptance criteria(Striking Velocities) for the A12519 weldments have been developed. Dynamic impact simulation of A12519 plate was achieved by using LS-DYNA, and predict the projectile velocity and the crack length. Also, Ballistic impact tests of A12519 plate have been performed, and compared with analysis results. Critical velocities of A12519 plate were acquired respectively, and striking velocities of A12519 weldments were calculated. Present work data will be used by basic data in ballistic impact test for A12519 weldments.

Isolation and characterization of the rice NPR1 promoter

  • Hwang, Seon-Hee;Hwang, Duk-Ju
    • Plant Biotechnology Reports
    • /
    • 제4권1호
    • /
    • pp.29-35
    • /
    • 2010
  • NPR1 is a positive regulator of systemic acquired resistance in Arabidopsis and rice. Expression of the rice gene OsNPR1 is induced by salicylic acid (SA). To identify the region of the OsNPR1 promoter involved in response to SA, we carried out deletion mutagenesis of the region 1005 bp upstream of the OsNPR1 start codon. Ciselement analysis revealed that the OsNPR1 promoter contains W-boxes and ASF1 motifs, both of which are known to be functional cis-elements of the WRKY and bZIP proteins, respectively. The deletion constructs 1005:LUC and 752:LUC, were induced by up to 4.3- and 3.8-fold, respectively, following SA treatment, suggesting that W-boxes and ASF1 motifs may play an important role in the strong induction of these constructs by SA. Using mutation analysis, we also showed that both the W-box and ASF1 motif are necessary for SA-induced expression of OsNPR1.

PERFORMANCE EVALUATION OF NEW SPACER GRID SHAPES FOR PWRS

  • Song, Kee-Nam;Lee, Soo-Bum;Lee, Sang-Hoon
    • Nuclear Engineering and Technology
    • /
    • 제39권6호
    • /
    • pp.737-746
    • /
    • 2007
  • A spacer grid, which is one of the most important structural components in a PWR fuel assembly, supports its fuel rods laterally and vertically. Based on in-house design experience, scrutiny of the design features of advanced nuclear fuels and the patents of other spacer grids, KAERI has devised its own spacer grid shapes and acquired patents. In this study, a performance evaluation of KAERI's spacer grid shapes was carried out from mechanical/structural and thermohydraulic view points. A comparative performance evaluation of commercial spacer grid shapes was also carried out. The comparisons addressed the spring characteristics, fuel rod vibration characteristics, fretting wear resistance, impact strength characteristics, CHF enhancement, and the pressure drop level of the spacer grid shapes. The results show that the performances of KAERI's spacer grid shapes are as good as or better than those of the commercial spacer grid shapes.

짧은 보강재가 부착된 가비온 옹벽의 모형실험 (Experimental Study on a Gabion Wall Reinforced by a Relatively Short Reinforcement)

  • 김준석
    • 한국지반신소재학회논문집
    • /
    • 제7권1호
    • /
    • pp.7-11
    • /
    • 2008
  • 가비온 옹벽은 경험적인 작업을 기초로 발전되어 왔으며, 현장적용이 활발하게 이루어지고 있다. 본 연구에서는 안정성에 중요한 요소인 인발저항력을 높이기 위하여 비교적 짧은 철망보강재로 보강된 가비온 옹벽 토체의 파괴거동을 이해하기 위하여 비교적 작은 규모의 실험을 실시하였다. 토체의 수평변위에 관한 자료를 얻었으며 이러한 자료들을 분석하였다. 또한 같은 조건에서 보강되지 않은 가비온 옹벽의 실험결과와 비교분석을 실시하였다.

  • PDF