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(1-x)$NdAlO_3$-$xCaTiO_3$세라믹스의 결정구조와 마이크로파 유전특성 연구
우창수,김민한,남산,최창학,이확주,박현민,Woo, Chang-Soo,Kim, Min-Han,Nahm, Sahn,Choi, Chang-Hack,Lee, Hwack-Joo,Park, Hyun-Min 한국세라믹학회 2000 한국세라믹학회지 Vol.37 No.12
(1-x)NdAlO$_3$-xCaTiO$_3$세라믹스의 결정구조와 마이크로파 유전특성을 조사하였다. 시편의 결정구조는 조성에 따라서 변화하였는데, 그 결정구조는 x$\leq$0.1일 때는 능면정(rhombohedral) 구조를, 0.3$\leq$x$\leq$0.7에서는 정방정 (tetragonal) 구조를 그리고, x$\geq$0.7일 때 다시 사방정 (orthorhombic) 구조로 바뀌었다. 또한 (1-x)NdAlO$_3$-xCaTiO$_3$세라믹스에서 이차상의 두 종류가 발견되었다. x$\leq$0.5인 시편에서는 Nd$_4$Al$_2$O$_{9}$상이, x$\geq$0.7인 시편에서는 Al-rich상이 발견되었다. x가 증가함에 따라, 유전율 ($\varepsilon$$_{r}$)과 공진주파수의 온도계수 ($ au$$_{f}$ )가 증가하였고, Q$\times$f 값은 x의 증가에 따라 증가하며, x=0.5일 때 최대값을 얻었다. 그리고 0.3NdAlO$_3$-0.7CaTiO$_3$에서 Q$\times$f=46,000, $\varepsilon$$_{r}$=45 그리고 $\tau$$_{f}$ =-1.5 ppm/$^{\circ}C$의 우수한 마이크로파 유전특성을 얻을 수 있었다.
우창수(Woo Chang Su),박동철(Park Dong Chul) 한국철도학회 2006 한국철도학회 학술발표대회논문집 Vol.- No.-
Rubber spring is used in primary suspension system for railway vehicle. This rubber spring has function which reduce vibration and noise, support the load carried in operation of rail vehicle. The non-linear properties of rubber material which are described as strain energy function are important parameter to design and evaluate of rubber spring. These are determined by material tests which are uni-axial tension and bi-axial tension and heat-ageing test. Also, the behaviors of load-displacement of rubber spring are evaluated by using commercial FEA code. It is shown that the results by simulations are agreement with test result.
우창수(Woo Chang-Su),김완두(Kim Wan-Doo) 한국철도학회 1998 한국철도학회 학술발표대회논문집 Vol.- No.-
Metal bonded rubber spring is used in primary suspension component of the high speed train. The aim of this study is to establish a finite element analysis technique for the metal bonded rubber spring. Some theoretical anaiyses were performed on the hyperelastic behavior in rubber material and test are carried out to acquire the constants in strain energy function for it. Also, finite element analysis were executed to evaluate the design parameter and behavior of deformation and stress distribution using by the commercial finite element code.
우창수(Chang-Su Woo),박현성(Hyun-Sung Park) 한국철도학회 2016 한국철도학회 학술발표대회논문집 Vol.2016 No.5
본 연구에서는 철도차량 1차 현가장치에 사용되는 원추형 고무스프링에 대해 유한요소해석과 특성시험을 수행하여 수직방향, 길이방향, 횡 방향의 강성을 예측하고 평가하였다. 또한, 설계 초기 단계에서 짧은 기간에 고무부품의 피로수명을 예측할 수 있는 방법을 개발하여 원추형 고무스프링에 대한 피로수명을 평가한 결과, 실제 피로시험을 통해 얻어진 피로수명과 예측수명이 비교적 정확하게 예측됨을 확인하였다. Conical rubber springs are used in primary suspensions for railway vehicle. Conical rubber spring have function which reduce vibration and noise, support load carried in operation of railway vehicle. Prediction and evaluation of characteristics and fatigue lifetime are very important in design procedure to assure the safety and reliability of the rubber spring. The computer simulation using the nonlinear finite element analysis program executed to predict and evaluate the load and displacement for the conical rubber spring. The non-linear properties of rubber which are described as strain energy functions are important parameters. Also, fatigue lifetime prediction methodology of vulcanized natural rubber was proposed by incorporating the finite element analysis and fatigue damage parameter of maximum Green-Lagrange strains appearing at the critical location determined from fatigue test. Predicted useful lifetime of the conical rubber spring showed a fairly good agreement with the experimental fatigue lifetime.
우창수(Changsu Woo),김완두(Wandoo Kim),김영길(Younggil Kim),신외기(Waegi Shin),이성훈(Seonghoon Lee) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11
The fatigue analysis and lifetime evaluation are very important in design procedure to assure the safety and reliability of the rubber components. Recently, the design, analysis and evaluation technology was required to achieve the high quality, fidelity, reliability of rubber products. However, rubber manufacturing companies of our country have uesd the method of trial and error and experience in the process of a compound mixing, manufacturing and improvement of rubber properties. The objectives of this study are to establish the test methods of rubber material and to make the database of rubber material properties and to evaluate the performance of rubber components and to construct the prediction system of fatigue life. Fatigue lifetime prediction methodology of the rubber component was proposed by incorporating the finite element analysis and fatigue damage parameter from fatigue test.
우창수(C. S. Woo),김완두(W. D. Kim),김기세(K. S. Kim) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.5
Rubber materials with excellent damping property are widely applied for vibration isolators. The<br/> dynamic characteristics of the rubber materials for vibration isolators were investigated. Dynamic test<br/> for rubber material with 5 different hardness were performed. In dynamic tests for test specimen,<br/> non-resonance method, was used to obtain the dynamic storage modulus and loss factor and the effect<br/> of dynamic vibration frequency, strain amplitude and temperature were investigated.
우창수 ( C. S. Woo ),김완두 ( W. D. Kim ),김기세 ( K. S. Kim ),권재도 ( J. D. Kwon ) 한국고무학회 2002 엘라스토머 및 콤포지트 Vol.37 No.3
우수한 신장성과 탄성복원 능력으로 여러 산업분야에 방진, 제진, 충격흡수 및 완충재료로 널리 사용되고 있는 고무재료에 대하여 주파수, 변형률 진폭 및 온도변화가 동특성에 미치는 영향을 실험을 통하여 검토하였다. 동특성 시험은 5종류의 경도에 대하여 인장·압축시험과 전단시험용의 천연고무 시험 편으로 비 공진법으로 수행하였다. 시험결과, 경도가 높을수록 동적 특성 값들이 크게 나타났으며 저장탄성계수와 손실계수는 주파수가 증가할수록 서서히 증가하였으며 변형률 진폭이 커질수록 감소하였다. 또한, 온도 특성은 -50℃ 영역에서 저장탄성계수가 급격히 상승하며 손실계수가 최대로 나타나는 전이역임을 알 수 있었다. Rubber materials with excellent damping property are widely applied for vibration isolators. The dynamic characteristics of the rubber materials for vibration isolators were investigated. Dynamic tests for rubber materials with five different hardness were performed. In dynamic tests for test specimen, non-resonance method was used to obtain the dynamic storage modulus and loss factor. Moreover, the effect of dynamic vibration frequency, strain amplitude and temperature were investigated. As results, the storage modulus and loss factor genearlly increase when the hardness and frequency increase, and the glass transition temperature is -50℃ by a large change in modulus and loss factor