• 제목/요약/키워드: Slip resistance performance

검색결과 76건 처리시간 0.026초

흑연과 삼황화안티몬의 상대적인 함량에 따른 비석면 유기질 마찰재의 제동특성에 관한 연구 (Effects of the Relative Amounts of Graphite and Antimony Trisulfide (Sb$_2$S$_3$) on Brake Performance of Non-asbestos Organic (NAO) Type Brake Linings)

  • 김성진;장호
    • Tribology and Lubricants
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    • 제17권5호
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    • pp.351-357
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    • 2001
  • Tribological behavior of NAO type brake linings containing different volume ratios of graphite and Sb$_2$S$_3$ was investigated using a scale dynamometer. Three different test modes consisting of stop, drag, and fade tests were employed to elucidate the effect of the solid lubricants on brake performance. Results of this work showed that the two solid lubricants, graphite and Sb$_2$S$_3$, significantly affected friction characteristics at various braking situations. Compared with the brake linings containing a single lubricant, the brake linings containing both solid lubricants showed better friction stability due to the synergistic effect of the two disparate lubricants during the stop and the drag test. In particular, in the case of containing two solid lubricants, the brake lining with higher contents of graphite showed better fade resistance than others.

엘리베이터의 정밀위치제어(精密位置制御)를 위한 유도전동기(誘導電動機) 구동방법(驅動方法) (A Drive Strategy of Induction Motor for High Accuracy position Control of Elevator)

  • 윤병도;김윤호;정재륜;채수형;김춘삼
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1992년도 하계학술대회 논문집 B
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    • pp.1215-1217
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    • 1992
  • This Paper described the hish performance position control for elevator using induction motor and driver. In this paper, the suitable Motor specifications for elevator drive are briefly discussed and high accuracy position control for both kinds of control method is analysed considering the parameter variation in the primary and secondary resistances. Since the pre-identified values of the motor constants are used to determine the control inputs, the performance degradation is caused by the parameter variation such as in the motor resistance. Particularly, the value of secondary resistance is considered significant because the control gain to determine the slip frequency is heavily dependent on that. The new proposed method uses on special small input signal for the parameter indentification and is expected to have the high accuracy position.

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두 종의 고체윤활제에 따른 마찰재의 마찰성능에 관한 실험적 고찰 (Experimental Investigation on Friction Performance of Brake Linings with Two Different Solid Lubricants)

  • 김성진;배은갑;윤호규;장호
    • 한국윤활학회:학술대회논문집
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    • 한국윤활학회 2001년도 제33회 춘계학술대회 개최
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    • pp.72-78
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    • 2001
  • An experimental investigation was conducted to examine the tribological behavior of NAO (non-asbestos organic) type brake linings containing different volume ratios of graphite and antimony trisulfide (Sb$_2$S$_3$). In order to investigate the effect of the solid lubricants on brake performance, three different friction tests (pressure, speed, and temperature sensitive tests) were carried out using a scale dynamometer. The test results showed that the friction characteristics were strongly affected by the type and the amount of solid lubricants in the brake lining. It was found that the brake linings with both solid lubricants were better in friction stability due to the complementary role of the two disparate lubricating properties at various pressure and speed conditions. In particular, the brake lining containing higher concentrations of graphite showed better fade resistance than others during high temperature friction test.

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회전자 자속 오차를 이용한 센서리스 유도전동기 제어 시스템 (Speed-sensorless Induction Motor Control System using the Rotor Flux Error)

  • 정강률
    • 전력전자학회:학술대회논문집
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    • 전력전자학회 2003년도 추계학술대회 논문집
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    • pp.123-126
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    • 2003
  • This paper proposes a speed-sensorless induction motor control system using the rotor flux error. The rotor flux observer uses the reduced- dimensional state estimator technique instead of directly measuring the rotor flux. The estimated rotor speed is obtained directly from the electrical frequency, the slip frequency, and the rotor speed compensation with the estimated q-axis rotor flux. To precisely estimate the rotor flux, the actual value of the stator resistance, whose actual variation is reflected, is derived. For fast calculation and improved performance of the proposed algorithm, all control functions are implemented in software using a digital signal processor (DSP) with its environmental circuits. Also, it is shown through experimental results that the proposed system gives good performance for the speed-sensorless induction motor control.

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Bond behavior of PP fiber-reinforced cinder concrete after fire exposure

  • Cai, Bin;Wu, Ansheng;Fu, Feng
    • Computers and Concrete
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    • 제26권2호
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    • pp.115-125
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    • 2020
  • To reduce the damage of concrete in fire, a new type of lightweight cinder aggregate concrete was developed due to the excellent fire resistance of cinder. To further enhance its fire resistance, Polypropylene (PP) Fibers which can enhance the fire resistance of concrete were also used in this type of concrete. However, the bond behavior of this new type of concrete after fire exposure is still unknown. To investigate its bond behavior, 185 specimens were heated up to 22, 200, 400, 600 or 800℃ for 2 h duration respectively, which is followed by subsequent compressive and tensile tests at room temperature. The concrete-rebar bond strength of C30 PP fiber-reinforced cinder concrete was subsequently investigated through pull-out tests after fire exposure. The microstructures of the PP fiber-reinforced cinder concrete and the status of the PP fibre at different temperature were inspected using an advanced scanning electron microscopy, aiming to understand the mechanism of the bonding deterioration under high temperature. The effects of rebar diameter and bond length on the bond strength of PP fiber-reinforced cinder concrete were investigated based on the test results. The bond-slip relation of PP fiber-reinforced cinder concrete after exposure at different temperature was derived based on the test results.

Experimental and numerical study on static behavior of grouped large-headed studs embedded in UHPC

  • Hu, Yuqing;Zhao, Guotang;He, Zhiqi;Qi, Jianan;Wang, Jingquan
    • Steel and Composite Structures
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    • 제36권1호
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    • pp.103-118
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    • 2020
  • The static behavior of grouped large-headed studs (d = 30 mm) embedded in ultra-high performance concrete (UHPC) was investigated by conducting push-out tests and numerical analysis. In the push-out test, no splitting cracks were found in the UHPC slab, and the shank failure control the shear capacity, indicating the large-headed stud matches well with the mechanical properties of UHPC. Besides, it is found that the shear resistance of the stud embedded in UHPC is 11.4% higher than that embedded in normal strength concrete, indicating that the shear resistance was improved. Regarding the numerical analysis, the parametric study was conducted to investigate the influence of the concrete strength, aspect ratio of stud, stud diameter, and the spacing of stud in the direction of shear force on the shear performance of the large-headed stud. It is found that the stud diameter and stud spacing have an obvious influence on the shear resistance. Based on the test and numerical analysis results, a formula was established to predict the load-slip relationship. The comparison indicates that the predicted results agree well with the test results. To accurately predict the shear resistance of the stud embedded in UHPC, a design equation for shear strength is proposed. The ratio of the calculation results to the test results is 0.99.

권선형 유도전동기 제어 시스템의 유지.보수 성능 향상을 위한 센서리스 벡터제어 (Sensorles Vector Control to Improve Maintenance Problem in Wound Rotor Type Induction Motor Control System)

  • 이홍희;박창근;정의헌
    • 전력전자학회논문지
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    • 제6권1호
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    • pp.57-63
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    • 2001
  • 산업 현장에서 널리 사용되고 있는 권선형 유도전동기 제어 시스템은 외부 2차 저항과 각종 접점으로 인해 효율과 유지 $.$ 보수상의 문제점을 안고 있다. 본 논문에서는 이러한 문제점을 해결하기 위해 기촌의 전동기 시스템에 별도의 장치를 부과하지 않고 2차 전류만을 검출하여 간단히 권선형 유도전동기를 제어할 수 있는 센서리스 벡터 제어 기법을 제안했다. 즉, 권선형 유도전동기활 제어하기 위해 필요한 기존의 외부 2차 서항이나 잔자접촉기들을 제거하고 회전자측을 완전히 단락시켜 2차 저항에 의한 전략손실이나 접점의 마모로 인한 유지.보수상의 문제점 을 제거했다. 또한. 제안된 센서리스 벡터제어 알고리즘은 기존의 얄고리즘과는 단리 여자 전류 및 슬립주파수 측 정에 전동기 2차 저항을 사용하지 않기 때문에 2차 저항 변동으로 인한 벡터제어의 불완전함을 제거했다. 아울러 디지털 시뮬레이션과 실험을 통해 제안된 알고리즘의 타당성을 확인을 하였다.

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안전한 노인요양시설 환경을 위한 실내 바닥마감재에 관한 연구 (A Study on Interior Flooring Materials for Safe Elderly Nursing Home Environment)

  • 정미렴
    • 한국주거학회논문집
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    • 제25권2호
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    • pp.19-26
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    • 2014
  • The number of elderly who wants to access to Nursing Homes (NH) will increase due to the rapid aging society and domestic changes. Those who move into NH expect 24/7 care service in safe environment. Providing space free from danger, especially from fall, for the frail elderly is essential. The purpose of this study is to categorize performance needs of flooring materials in the aspect of safety, and analyze materials so that adequate ones for each space in NH can be suggested. Performance needs are as follows; slip resistance (dry/wet), fire resistance, resilience, water resistance, soil retardant, anti-bacterial, gloss, sound absorbtion. maintenance, durability, ease replacement, color and pattern variety, visual and tactual texture, tactile warmth, IAQ, sustainable material (before use), impact to nature (after use). They are categorized under function, economy, sensibility and sustainability. It was found that there are better materials than common ones that has been used repeatedly in NHs, such as vinyl sheets and VCT. In overall, Cork flooring and nylon carpet met all four categories, followed by wool carpet, rubber and linoleum. For bedroom, wood flooring, Cork, rubber, wool carpet, nylon carpets were suggested. In bathroom with shower, rubber, vinyl sheet and porcelain tiles were safe materials. As living/dining room and corridor floors, wool carpet, nylon carpet, cork flooring would be excellent as they are resilient and durable. The result of this paper can be used by both NH managers and material companies, resulting better quality of life of the elderly by providing safe environment.

GFRP를 이용한 경량합성바닥의 휨성능에 대한 실험적 평가 (An Experimental Evaluation on Flexural Performance of Light-Weight Void Composite Floor using GFRP)

  • 류재호;박세호;주영규;김상대
    • 한국강구조학회 논문집
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    • 제23권1호
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    • pp.125-135
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    • 2011
  • 최근 타워형 아파트구조에 많이 사용되고 있는 무량판 구조시스템을 대신해 층고절감 및 장스팬 구현 그리고 내화성능향상을 목적으로 GFRP를 이용한 경량합성바닥을 개발하였다. GFRP를 이용한 경량합성바닥은 웨브에 개구부를 가지는 비대칭 강재보 하부에 GFRP를 부착하고 슬래브에 경량체를 삽입한 중공합성바닥이다. 이에 개발된 합성바닥의 휨성능을 평가하기 위해 GFRP, 중공률, 웨브의 개구부 등을 변수로 실대 실험을 수행하였다. 그 결과 GFRP를 이용한 합성보 실험체는 기준 실험체에 비해 휨내력 및 강성 측면에서 10% 높은 성능을 나타냈으며, 구조물이 항복할 때까지 완전합성거동하였다. 항복 이후 웨브개구부 주변의 응력집중현상에 의해 연성이 감소하는 현상이 나타났으며, 최대내력점까지 미끄러짐의 발생은 미소하였다. 내력설계 측면에서는 안전율을 고려해 해석값의 85%를 설계내력으로 평가하는 것이 타당한 것으로 나타났다.

예방적 유지보수를 위한 아스팔트 표면강화공법의 실내 성능 평가 (A Study on Performance Evaluation of New Asphalt Surface Reinforcement Method (ASRM) for Preventive Maintenance)

  • 김경남;조신행;김낙석;이두성
    • 대한토목학회논문집
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    • 제38권2호
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    • pp.311-317
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    • 2018
  • 아스팔트 콘크리트 포장의 예방적 유지보수방법 중 하나인 표면강화공법의 실내 성능 평가를 수행하였다. 표면강화공법과 아스팔트 콘크리트 포장과의 부착력 평가 결과 미끄럼방지 포장 및 교면방수재료 기준을 상회하는 부착성능을 나타내었다. 윤하중재하실험과 박리저항성, UV저항성 실험을 통해 교통 및 환경하중에 대해 충분한 내구성을 확보할 수 있는 것을 확인하였다. 표면강화공법은 내투수성과 내화학성이 뛰어나 포장내로 수분 침투를 막고 화학물질로부터 포장을 보호할 수 있으며, 노화된 아스팔트 바인더의 재생효과가 있어 재생 아스팔트 콘크리트에 적용하였을 때 재래식 가열 아스팔트 콘크리트 혼합물에 비하여 약 5%의 터프니스를 증가시켰다. 아스팔트 표면강화공법은 아스팔트 콘크리트 포장의 내구성을 향상시킬 수 있는 특성을 갖는 것으로 나타났다.