• Title, Summary, Keyword: ER

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Estimation of Performance Variation of ER Clutch due to Temperature Increase of ER Fluid (ER 유체의 온도상승에 의한 ER 클러치의 성능변화 예측)

  • 이규한;심현해;김창호;임윤철
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • pp.151-166
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    • 1997
  • ER clutch is a device using ER fluid, so called "intelligent material" and is a controlled system with electric field strength. Current problem of this device is that the temperature of ER fluid increases when ER clutch is operating and affects the performance of ER clutch. This study was undertaken to estimate this performance variation due to temperature increase of ER fluid. Analytic power transmission relationships and the temperature increase model using the rheological model of ER fluid were developed and the dynamic model of proposed ER clutch system was constructed, also. With this relationships, effects of changing geometric, kinetic parameters of ER clutch and ER fluid properties were described and performance variations due to temperature increases of ER fluid were estimated. In conclusion, compared with neglecting temperature increase effects, a performance of ER clutch was very differential. Therefore, to achieve uniform performance of ER clutch, we have to improve thermal stability of ER fluid with a view point of material development and design carefully ER clutch considering temperature increase effects with a view point of mechanical design skill.ign skill.

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The Effect of Compressing ER Electrode on Electrorheological Properties of Anhydrous ER Fluids (ER 유체용 압축전극이 ER 유체의 전기유변학적 특성에 미치는 영향)

  • Ahn, Byeng-Gil
    • Tribology and Lubricants
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    • v.18 no.1
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    • pp.16-23
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    • 2002
  • For increasing the yield stress of ER fluids, the compressing ER electrode was developed and the compressing electrorheological (ER) behavior of anhydrous ER fluids in silicone oil of phosphorous ester cellulose powder was investigated. Under constant electric field, not only the current density but also the yield stress of anhydrous ER fluids were studied as varying the compressing length of ER electrode distance. From the experimental results the compressing of ER electrode had a large influence to the ER properties of anhydrous ER fluids. The current density was proportional to the compressing length of ER electrode under constant electric field and volume fraction also tile compressing yield stress was proportional to the volume fraction of dispersed particles under constant electric field and compressing length. When the ER electrode was compressed with 150mm after charging the electric field, 4 kV, tile yield stress of phosphoric ester cellulose ER fluids increased to thirteen times comparing with the yield stress measured at normal electrode.

Do Clinical Features and Survival of Single Hormone Receptor Positive Breast Cancers Differ from Double Hormone Receptor Positive Breast Cancers?

  • Ng, Char-Hong;Pathy, Nirmala Bhoo;Taib, Nur Aishah;Ho, Gwo-Fuang;Mun, Kein-Seong;Rhodes, Anthony;Looi, Lai-Meng;Yip, Cheng-Har
    • Asian Pacific Journal of Cancer Prevention
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    • v.15 no.18
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    • pp.7959-7964
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    • 2014
  • The significance of the single hormone receptor positive phenotype of breast cancer is still poorly understood. The use of hormone therapy has been found to be less effective for this type, which has a survival outcome midway between double positive and double negative phenotypes. The aim of this study was to investigate differences in patient and tumor characteristics and survival between double-receptor positive (ER+PR+), double receptor negative (ER-PR-) and single receptor positive (ER+PR- and ER-PR+) breast cancer in an Asian setting. A total of 1,992 patients with newly diagnosed stage I to IV breast cancer between 2003 and 2008, and where information on ER and PR were available, were included in this study. The majority of patients had ER+PR+ tumors (n=903: 45.3%), followed by 741 (37.2%) ER-PR-, 247 (12.4%) ER+PR-, and 101 (5.1%) ER-PR+ tumors. Using multivariate analysis, ER+PR- tumors were 2.4 times more likely to be grade 3 compared to ER+PR+ tumors. ER+PR- and ER-PR+ tumors were 82% and 86% respectively less likely to be grade 3 compared with ER-PR- tumors. ER-PR+ tumours were associated with younger age. There were no survival differences between patients with ER+PR+ and ER-PR+ tumors. However, ER+PR- tumors have poorer survival compared with ER+PR+ tumours. ER-PR- tumours had the worst survival. Adjuvant hormonal therapy with tamoxifen was found to have identical survival advantage in patients with ER+PR+ and ER-PR+ tumors whereas impact was slightly lower in patients with ER+PR- tumors. In conclusion, we found ER+PR- tumors to be more aggressive and have poorer survival when compared to ER+PR+ tumors, while patients with ER-PR+ tumours were younger, but had a similar survival to their counterparts with ER+PR+ tumours.

Maneuver Analysis of Full-Vehicle Featuring Electrorheological Suspension and Electrorheological Brake (ER 현가장치 및 ER 브레이크를 적용한 전체차량의 거동분석)

  • Sung, Kum-Gil;Choi, Seung-Bok
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.1125-1130
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    • 2007
  • This paper presents a maneuver analysis of a full-vehicle featuring electrorheological (ER) suspension and ER brake. In order to achieve this goal, an ER damper and an ER valve pressure modulator are devised to construct ER suspension and ER brake systems, respectively. After formulating the governing equations of the ER damper and ER valve pressure modulator, they are designed and manufactured for a middle-sized passenger vehicle, and their field-dependent characteristics are experimentally evaluated. The governing equation of motion for the full-vehicle is then established and integrated with the governing equations of the ER suspension and ER brake. Subsequently, a sky-hook controller for the ER suspension and a sliding mode controller for the ER brake are formulated and implemented. Control performances such as vertical displacement and braking distance of vehicle are evaluated under various driving conditions through computer simulations.

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Comparison of In-situ Er-doped GaN with Er-implanted GaN Using Photoluminescence and Photoluminescence Excitation Spectroscope (In situ Er 도핑된 GaN와 Er이 이온 주입된 GaN의 PL과 PLE 비교에 대한 연구)

  • 김현석;성만영;김상식
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.16 no.2
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    • pp.89-96
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    • 2003
  • Photoluminescence (PL) and photoluminescence excitation (PLE) spectroscopy have been performed at 6 K on the 1540 nm $^4$I$\_$(13/2)/\longrightarrow$^4$I$\_$(15/2)/ emission of Er$\^$+3/ in in situ Er-doped GaN The PL and PLE spectra of in situ Er-doped GaN are compared with those of Er-implanted GaN in this study. The lineshapes of the broad PLE absorption bands and the broad PL bands in the spectra of the in situ Er-doped GaN are similar to those in Er-doped glass rather than in the Er-implanted GaN. The PL spectra of this in situ Er-doped GaN are independent of excitation wavelength and their features are significantly different from the site-selective PL spectra of the Er-implanted GaN. These PL and PLE studies reveal that a single type of Er$\^$3+/ sites is present in the in situ Er-doped GaN and these Er sites are different from those observed in the Er-implanted GaN. In addition, the comparison of the PL single strength illustrates that the excitation of Er$\^$3+/ sites through the energy absorption of defects in Er-implanted GaN.

Power Transmission Mechanism of Electrorheological Clutch (Part II: Estimation of Performance Variation due to Temperature Rise of Eiectrorheological Fluid) (전기유변성 클러치의 동력전달 메커니즘 제2보:전기유변성 유체의 온도상승에 의한 성능변화 예측)

  • 이규한;심현해;김창호;임윤철
    • Tribology and Lubricants
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    • v.13 no.3
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    • pp.73-84
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    • 1997
  • ER clutch is a device using ER fluid, so called "intelligent material" and is a controlled system with electric field strength. Currently, the temperature of ER fluid increases and affects the performance of ER clutch when ER clutch is operating. This study was undertaken to estimate this performance variation due to temperature rise of ER fluid. An analytic heat transfer model of concentric cylinder type ER clutch was developed and with this model, effects of changing geometric, kinetic parameters of ER clutch and ER fluid properties were described. In conclusion, compared with neglecting thermal effects, a performance of ER clutch was very differential and for uniform performance of ER clutch, we have to improve thermal stability of ER fluid. ER fluid.

The Effect of Compressing ER Electrode on the Electrorheological Properties of ER Fluids (ER 유체용 압축전극이 ER 유체의 전기유변학적 특성에 미치는 영향)

  • 안병길
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • pp.138-145
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    • 2001
  • For increasing the yield stress of ER fluids, the compressing ER electrode was developed and the compressing electrorheological (ER) behavior of anhydrous ER fluids in silicone oil of phosphorous ester cellulose powder was investigated. Under constant electric field, not only the current density but also the yield stress of anhydrous ER fluids were studied as varying the compressing length of compressing ER electrode. From the experimental results, the compressing of ER electrode had a large influence to the ER properties of anhydrous ER fluids. The current density was proportional to the compressing length of ER electrode under constant electric field and volume fraction also the compressing yield stress was proportional to the volume fraction of dispersed particles under constant electric field and compressing length. When the ER electrode was compressed with 150mm after charging the electric field, 4 kV, the yield stress of phosphoric ester cellulose ER fluids increased to thirteen times comparing with the yield stress measured at normal electrode.

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Photoluminescence and Photoluminescence Excitation Spectra of Mg-codoped GaN:Er (Mg가 첨가된 GaN:Er 발광 현상에 관한 연구)

  • 김상식;성만영;홍진기
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.33-38
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    • 2000
  • The ~1540 nm Er$^{3+}$ photoluminescence (PL) and photoluminescence excitation (PLE) spectra of Er-implanted Mg-codoped GaN (GaN:Er+Mg) exhibit that the excitation efficiency of a specific Er$^{3+}$ center among different Er$^{3+}$ centers existing in Er-implanted GaN is selectively enhanced, compared to Er-implanted undoped GaN (GaN:Er). In GaN:Er+Mg, the 1540 nm PL peaks characteristic of the so-called "violet-pumped" Er$^{3+}$ center and the ~2.8-3.4 eV (violet) PLE band are significantly strengthened by the Mg-doping. The intra-f absorption PLE bands associated with this "violet-pumped" center are also enhanced by this doping. The 1540 nm PL peaks originating from the violet-pumped center dominate the above-gap-excited Er$^{3+}$ PL spectrum of GaN:Er+Mg, whereas it was unobservable under above-gap excitation in GaN:Er. All of these results indicate that Mg doping increases the efficiency of trap-mediated excitation of Er$^{3+}$ emission in Er-implanted GaN.planted GaN.

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Maneuver Analysis of Full-vehicle Featuring Electrorheological Suspension and Electrorheological Brake (ER 현가장치 및 ER 브레이크를 적용한 전체차량의 거동분석)

  • Sung, Kum-Gil;Choi, Seung-Bok
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.17 no.5
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    • pp.464-471
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    • 2007
  • This paper presents a maneuver analysis of a full-vehicle featuring electrorheological(ER) suspension and ER brake. In order to achieve this goal, an ER damper and an ER valve pressure modulator are devised to construct ER suspension and ER brake systems, respectively. After formulating the governing equations of the ER damper and ER valve pressure modulator, they are designed and manufactured for a middle-sized passenger vehicle, and their field-dependent characteristics are experimentally evaluated. The governing equation of motion for the full-vehicle is then established and integrated with the governing equations of the ER suspension and ER brake. Subsequently, a sky-hook controller for the ER suspension and a sliding mode controller for the ER brake are formulated and implemented. Control performances such as vertical displacement and braking distance of vehicle are evaluated under various driving conditions through computer simulations.

Flow Characteristics of Dispersive ER Fluid Clearance between ER-Valve (ER-Valve 간극내에서 분산계 ER유체의 유동특성)

  • 장성철;염만오;이종두;장성수
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.1123-1126
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    • 2003
  • In this research 4 plate type ER-Valves which have same surface but different width and length are designed and an experimental apparatus is constructed. With this experimental apparatus, flow rate and pressure drop of ER fluid flowing in ER-Valve are measured by varying electric field strength of ER-valve, and relation between valve types and pressure drop is also experimented. ER fluid is made silicon oil mixed with 40wt% starch having hydrous particles. The pressure drop according to the strength of electric field by differential pressure gauge in the present ER-Valve was used. This test reviewed experiment for the special changes of ER fluids in the steady flow condition.

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