http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Ti-6Al-4V 합금의 내부 미소결함에 따른 초음파 신호 특성 연구
최상우,이준현,--,-- 한국비파괴검사학회 2001 한국비파괴검사학회지 Vol.21 No.6
Ti합금은 고온환경에서 고강도가 요구되는 항공기의 엔진 부품등의 소재로 적용되고 있다. Ti합금은 이와 같이 기계적 성능이 우수함에도 불구하고 α상과 β상의 조성에 의한 두 상의 띠세 구조에 의한 초음파 산란으로 초음파를 이용한 비파괴 평가에서 피로균열 검출이 어려운 단점이 있다. 합금내의 결정립에서 산란되는 초음파 신호에 의하여 결함이 존재하지 않는 경우에도 산란 신호가 검출되는 결정립 산란 잡음 신호가 존재하며, 이들 결정립 산란 잡음신호는 합금내부에 존재하는 기공 및 불순물 등의 결함 검출을 어렵게 하는 요인이다. 본 연구에서는 Ti합금의 효율적인 초음파를 이용한 비파괴 평가의 적용을 위하여 Ti합금 시험편에 대하여 초음파 전파속도 측정 및 미세 드릴 가공에 의한 인공 결함의 검출능 평가 등을 수행하였다. Ti alloy is used for essential parts of aircraft for high temperature environment. Although Ti alloy has excellent performance in regard to mechanical properties, it is difficult to find fatigue cracks by nondestructive ultrasonic inspection due to its two-phase microstructure, which consists of hard alpha and beta phases. Sound energy reflected from microstructural features in the component produces a background inspection noise which is seen even when no defects are present. This noise can inhibit the detection of critical internal defects such as pores cracks or inclusions. To obtain fundamental data on ultrasonic inspection of Ti alloy, ultrasonic testing was performed using a specimen with small drill holes and ultrasonic wave propagation velocities were measured.
Application of Matrix Thinking Method to Introduction Program in Engineering Education
Y. Satoh,K. Takahashi,Y. Takahata,김윤해,S. Kubota 한국공학교육학회 2010 공학교육연구 Vol.13 No.2
From a lot of survey, it is obvious that most students in universities lose their desire for learning just after enteringtheir universities. In order to solve this problem, we developed a novel educational tool for the students, named “Thethinking method based on matrix diagram”. If they try hard with the help of this tool, they will be able to learn how todesign and manage their splendid university lives in addition to get the basic knowledge and to improvetheir basic abilities.It is also found that they can earn the shared knowledge mutually after learning a common method, which supports to makethem to improve their communication abilities drastically.
SHAPE-SELECTIVE ISOPROPYLATION OF BIPHENYL OVER DEALUMINATED H-MORDENITES
Sugi, Y,Kim, J.H,Matsuzaki, T,Hanaoka, T,Kubota, Y,Tu, X,Matusmoto, M 전남대학교 촉매연구소 1993 촉매학술발표회 Vol.- No.10
Shape-selective alkylation using zeolitc is a useful way to introduce functional groups symmeetrically to aromatic hydrocarbons. One of important development on shape-selective catalysis achieved recently is the success in isopropylation of polynuclear aromatics, such as biphinyl and naphthalene over H-mordenite[1-5]. However, the mechanism of the catalysis related to solid acid sites and steric requirement in zeolite pores have not been fully understood. In this paper, we examine the isopropylation of biphenyland the ismerization of 4,4'-diisopropylbiphenyl over highly dealuminated H-mordenites, and discuss the mechanism of the catalysis.
H. Kawai,Y. Choi,Y. B. Kim,Y. Kubota 제어로봇시스템학회 2008 제어로봇시스템학회 국제학술대회 논문집 Vol.2008 No.10
Speedy operation efficiency is constantly required of the container crane operators who work for cargo handling in the port. They are experts in suppressing the sway motion which is generated in the process of the handling. This undesirable motion may deteriorate the operation efficiency due to strained nerves of the operator. Therefore, an anti-sway controller has been required on practical job-site. To accomplish an adequate anti-sway control, sensors are also required to be able to measure the position of a crane spreader moving on. In this paper, we propose a position measurement system with an image sensor. The image sensor detects two devised landmarks attached to the upside surface of a spreader to measure the displacement and height to one. The image processing technique used for the sensor is a kind of robust template matching method, named Vector Code Correlation (VCC), devised to consider the conditions of real environments. We employ the simple mechanism, so that the system can be easily applicable to existing container cranes. The details and performance of the measurement system are introduced together with the experimental results performed with the pilot system. We will also show that the system has the sufficient efficiency and accuracy for the use on practical job-site.
Structural Changes and Microstructures of Ba1−xSrxAl2O4 for 0 < x < 0.4
E. Tanaka,Y. Ishii,H. Tsukasaki,S. Mori,M. Osada,H. Taniguchi,Y. Sato,Y. Kubota 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.66 No.9
We have investigated the structural changes and the microstructures of Ba1−xSrxAl2O4 for 0 < x < 0.4 by using transmission electron microscope (TEM) and synchrotron radiation powder X-ray diffraction experiments. The TEM experiments revealed the existence of a structural phase boundary at approximately x = 0.1, at which the superlattice reflection spots at the 1/2 0 0 −type positions change into diffuse streaks along three equivalent <110> directions in the hexagonal structure. In addition, real-space images of Ba1−xSrxAl2O4 for 0 < x < 0.4 reveal that BaAl2O4 should be characterized as a modulated structure with triple-q modulation vectors along the <100> directions and on the other hand, Ba1−xSrxAl2O4 for 0.1 < x < 0.4 be characterized as an intermediate (precursor) state with a rigid unit mode due to structural instability. These experimental results implied that the partial substitution of Sr2+ for Ba2+ should suppress a structural instability due to the AlO4 tetrahedral network and decrease the structural phase transition temperature.