• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.12 no.3
• /
• pp.215-220
• /
• 1992

The rational methods of pavement design and analysis using the resilient modulus have been increasingly adopted by major advanced countries and many researches concerning the resilient characteristics of pavement materials as well as developement of reliable testing method have been actively performed. Accordingly, fundamental researches on the resilient modulus characteristics of domestic subgrade soils are very important. With want of aggregate due to the national constuction projects, it is siginificant to examine on the utilization of coal ash as pavement materials. The purpose of this study is to examine resilient modulus characteristics and to evaluate the relationship between MR and CBR by AASHTO testing method. The materials for this investigation are Coal Ash (Fly Ash, Bottom Ash) from 5 thermal-power-plants and 4 decomposed-granite-soils from central regions of Korea.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.07a
• /
• pp.1050-1053
• /
• 2001

There is great interest in developing magnetoresistance(MR) sensor, using ferromagnetic, electrically non-magnetic conducting and antiferromagnetic films, especially for the use in weak magnetic fields. Here, we report single and Wheatstone-bridge type of MR sensors made in Si(001)/HiO(300$\AA$)/NiFe bilayers. Angular dependence of MR profiles was measured in Si(001)/NiO(300$\AA$)/NiFe(450$\AA$) films as a function of an angle between current and applied field direction, also, linearity was determined. AMR characteristics of single MR sensors was well explained with single domain model. Good linearity in 45$^{\circ}$Wheatstone-bridge type of MR sensors consisting of 4 single MR sensors made in Si(001)/NiO(300$\AA$)/NiFe(450$\AA$) was shown in the range of about $\pm$50 Oe.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2001.11a
• /
• pp.41-41
• /
• 2001

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.11a
• /
• pp.260-263
• /
• 2002

There is great interest in developing magnetoresistance(MR) sensor, using ferromagnetic, electrically non-magnetic conducting and antiferromagnetic films, especially for the use in weak magnetic fields. Here, we report single and Wheatstone-bridge type of MR sensors made in Si(001)/NiO($300{\AA}$)/NiFe bilayers. Angular dependence of MR profiles was measured in Si(001)/NiO($300{\AA}$)/NiFe($450{\AA})$ films as a function of an angle between current and applied field direction, also, linearity was determined. AMR characteristics of single MR sensors was well explained with single domain model. Good linearity in $45^{\circ}$ Wheatstone-bridge type of MR sensors consisting of 4 single MR sensors made in Si(001)/NiO($300{\AA}$)/NiFe($450{\AA})$ was shown in the range of about ${\leq}{\pm}5$ Oe.

• Korean Journal of Metals and Materials
• /
• v.50 no.5
• /
• pp.401-406
• /
• 2012

When viewed using a magnetic resonance imaging (MRI) system, invasive materials inside the human body, in many cases, severely distort the MR image of human tissues. The degree of the MR image distortion increases in proportion not only to the difference in the susceptibility between the invasive material and the human tissue, but also to the intensity of the magnetic field induced by the MRI system. In this study, by blending paramagnetic Ti particles with diamagnetic graphite, we synthesized $Ti_{100-x}C_x$ composites that can reduce the artifact in the MR image under the high-strength magnetic field. Of the developed composites, $Ti_{70}C_{30}$ showed the magnetic susceptibility of ${\chi}=67.6{\times}10^{-6}$, which corresponds to 30% of those of commercially available Ti alloys, the lowest reported in the literature. The level of the MR image distortion in the vicinity of the $Ti_{70}C_{30}$ composite insert was nearly negligible even under the high magnetic field of 4.7 T. In this paper, we reported on a methodology of designing new structural materials for bio-applications, their synthesis, experimental confirmation and measurement of MR images.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2000.11a
• /
• pp.355-358
• /
• 2000

Magnetoresistance changes of NiFe thin films were investigated as a function of deposition temperature. DC magnetron sputtering was employed to fabricate Ta/NiFe(t)/Ta thin films on Si(001) substrates with in-situ field or with no-field. The thickness(t) of NiFe films was a range of 4 to 15nm. Substrate temperature was a range of 30 to 400$^{\circ}C$. MR measurement was carried out as a function of angle $\theta$, between external field and current direction. MR ratio increased with increasing substrate temperature, also, max. MR ratio was observed in samples deposited at 300$^{\circ}C$. With increasing upto 400$^{\circ}C$, MR ratio was rapidly decreased in the case of thinner NiFe films. In non-field deposited NiFe films, both angle $\theta$=0, 90。, there was no significant change in MR curves. However, MR curves of in-situ field deposited NiFe films were different in both angles $\theta$=0 and 90。

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.20 no.11
• /
• pp.1046-1051
• /
• 2010

This paper presents design and performance evaluation of magnetorheological(MR) damper for integrated isolation mount. The MR damper needs two functions for the integrated isolation mount. The one is vibration absorption and the other is isolation of vibration transmission. For vibration absorption, the MR damper requires wide damping force range. And for isolation of vibration transmission, the friction of MR damper needs to be eliminated. In order to achieve this goal, a novel type of MR damper is originally designed in this work. Subsequently, the MR damper is mathematically modeled and its damping force characteristics are evaluated. In addition, the vibration control performance of the MR damper associated with the stage mass is evaluated. From the result, this paper evaluates the performance of MR damper for integrated isolation mount.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2007.05a
• /
• pp.1137-1141
• /
• 2007

This paper is concerned with the experimental research of magnetorheological elastomers (MREs). The modulus of the MR elastomers can be controlled by an applied magnet field, so that it can be effectively used for vibration suppression applications. The MR elastomer in this experiment is a mixture of KE-1300 silicone, carbonyl iron powder (300mesh) and a silicone hardener (CAT-1300). Three specimens were manufactured and tested by using the vibration testing instruments. The magnetic field was generated by the permanent magnets. The experimental results show that the natural frequencies of the test article with MR elastomer changes by the applied magnetic field. The performance of the MR elastomer can be increased by stronger magnetic fields. This is under investigation.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.52 no.2
• /
• pp.51-57
• /
• 2010

Many models have been used to represent the effects of confining stress, bulk stress, and shear stress on the value of the resilient modulus (Mr). This study was conducted to estimate Mr of the recycled materials such as recycled concrete aggregate (RCA) and recycled asphalt pavement (RAP) through the repeated load cyclic test. Also, two models were applied to estimation of Mr for comparing between measured Mr values and predicted Mr values. The first model (A-model) can provide a quick and easy estimation of the Mr based on the bulk stress, while the second model (N-model) includes not only the bulk stress but also the shear stress. Statistical analysis indicated that all results using the both of models are significant at a 95 % confidence level. Therefore, the both of models could be used as an effective prediction model of Mr for RCA and RAP. Especially, the Model 2 including the parameters of the bulk stress and the shear stress could give more reliable estimation at the high range of Mr values.

• Proceedings of the KSMRM Conference
• /
• 2002.11a
• /
• pp.50-56
• /
• 2002

최근 3-4년간 MR의 hardware와 software의 급격한 발전으로 마침내 작년 말에 3.0 Tesla whole body MR 장비가 미국 FDA의 공인을 받았다. 한국에서도 일찍부터 3T MR장비의 개발이 이루어 졌고 이미 설치되어 연구와 임상이 이용되고 있다. 여러 회사에서 개발 및 연구된 전신 3.0T MR 장비가 여러가지 가능성을 보이고 임상 도입 단계에 있지만 아직까지 실지 임상에서는 뇌신경계 분야가 주류를 이루고 있다. 지금 뇌신경계 분야에서 보편적으로 늘리 사용되고 있는 1.5T MR 장비는 모든 면에서 상당히 안정적으로 임상 및 연구에 이용되고 있다. 1-2년 전만 해도 3.0 T MR기기는 뇌신경계 영역에서도 임상적으로 늘리 사용되기에는 안정적인 면에서는 1.5T 기기에 비해서 떨어지는 것이 사실이었다. 그래서 주로 연구실 영역에서 많이 이용되고 있었다. 그러나 지금 본원에 설치 완료되어 임상에 적용한지 6개월 정도 이용한 예에서 보면 (about 2300 cases/6months) hardware, software적인 면에서 아직 조금의 불편함이 있지만 많은 부분이 충분히 인지되고 개선이 가능한 부분으로 거의 불편함이 사라질 것으로 기대되고 있고, 불편함을 넘을 수 있는 여러 가지 장점이 있다고 본다. 고자장 (>3.0 T) MRI의 매력은 자장에 비례적으로 SNR, spectral resolution이 높아지고, T1, BOLD등에 의한 대조도가 향상한다는 것이다. SNR의 증가는 temporal, spatial 분해능을 증가시키고, spectral resolution이 높아짐에 따라 MR spectroscopy상에서 주요 대사물질 이외 작은 대사물질에 관한 스펙트럼의 분석을 향상시킨다. 이처럼 고자장 MR은 근본적인 장점을 가지고 있고 이러한 장점이 고자장 MR 시대로 가야 할 이유을 모두 설명하고 있다고 생각된다.세포질등이 있으며, 이들중에서 lysosomes, peroxisomes, 그리고 미토콘드리아가 특정한 유전성 백질질환에 중요한 역할을 하는 것이 밝혀졌다. 이러한 질환들은 최소한 각 소기관에 의한 질환군으로 분류될 수 있다.SXR이 ER의 transactivation 효과를 약간 촉진한 반면 MDA-MB-231세포는 SXR을 제외한 CAR와 PPAR${\gamma}$에 의해 ER의 transactivation 효과가 약간 증가되는 경향을 보였다. 이러한 결과는 유방암세포에서는 CAR, SXR, PPAR${\gamma}$과 같은 xenobiotic nuclear receptor에 의한 ER transactivation 효과가 간암세포와는 다르게 나타나며, 유방암의 종류에 따라서 endogenous CAR, SXR, PPAR${\gamma}$수용체가 다르게 발현됨으로써 이들에 대한 반응이 서로 상이한 특징을 나타낼 수 있을 것으로 사료된다. 따라서 estrogen receptor에 의해 매개되는 estrogn의 전사활성조절기전이 표적세포에 따라 다른 경로를 포함 할 수 있음을 시사한다.서 흡착 능력이 우수하게 나타났으며, 황화수소는 펄라이트, 왕겨, 소나무수피에서 상대적으로 우수한 것으로 나타났으며, 혼합충전재는 암모니아의 경우 코코넛과 펄라이트의 비율이 7：3인 혼합 재료 3번과 소나무수피와 펄라이트의 비율이 7：3인 혼합 재료 6번에서 다른 혼합 재료에 비하여 우수한 것으로 나타났다. 4. 코코넛과 소나무수피의 경우 암모니아 가스에 대한 흡착 능력은 거의 비슷한 것으로 사료되며, 코코넛의 경우 전량을 수입에 의존하고 있다는 점에서 국내 조달이 용이하며, 구입 비용도 적게 소요되는 소나무수피를 사용하는 것이 경제적이라고 사료된다. 5. 마지막으로 악취제거 미생물균주를 접종한 소나무수피 50%와 펄라이트