• 한국공작기계학회논문집
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• 제17권3호
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• pp.20-26
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• 2008

Nanoimprint lithography(NIL) is becoming next generation lithography of significant interest due to its low cost and a potential patterning resolution of 10nm or less. Success of the NIL relies on the adequate conditions of pressure, temperature and time. To have the adequate conditions for NIL, one has to understand the polymer flowing behavior during the imprinting process. In this paper, an analytical approach of polymer flow in thermal NIL was performed based on the squeeze flow with partial slip boundary conditions. Velocity profiles and pressure distributions of the polymer flow were obtained and imprinting forces and residual thickness were predicted with the consideration of the slip velocity between the polymer and the mold/substrate. The results show that the consideration of the slip is very important for investigating the polymer flow in Thermal NIL.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.830-832
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• 2014

In this study, friction stick-slip vibration're interpretation of the phenomenon, we used a statistical model of friction. In a previous study using a definite friction factor, but to a dynamic simulation using a constantly changing during the integration time by a Monte Carlo simulation method, not the average coefficient of friction and the dynamic friction coefficient and a constant value in this study.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.866-867
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• 2006

This work will report a highly textured ${\beta}-Si_3N_4$ ceramic by aqueous slip casting in a magnetic field and subsequent pressureless sintering, Effects of the sintering aids, polymer dispersant, pH and stirring time on the stability of the $Si_3N_4$ slurries were studied. The textured ${\beta}-Si_3N_4$ with 97 % relative density could be obtained by slip casting in a magnetic field of 12 T and subsequent sintering at $1800^{\circ}C$ for 1 h. The textured microstructure is featured by the alignment of c-axis of ${\beta}-Si_3N_4$ crystals perpendicular to the magnetic field, and the Lotgering orientation factor, f, is determined to be 0.8.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 추계학술대회 논문집 학회본부 B
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• pp.405-407
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• 2000

The most generally implemented method to detect the ground speed of the railway vehicles is to use the rotary type speed sensor attached to wheel axle. The Slip or sliding phenomenon on the railway vehicles occurs frequently caused by the weak viscosity of the wheel. Thus, precisely to control the car, the slip/sliding detection system is required. In this paper we proposed for the speed data management system, which uses rotary type speed sensor. Proposed speed management system can detect the slip/sliding with wheel axle as well as correct the generated speed error during in error time, to provide accurate speed and precise location data. The effectiveness for adapting to the railway system is clarified by the computer simulation.

• Earthquakes and Structures
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• 제24권5호
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• pp.365-375
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• 2023

Energy dissipation systems increase the energy dissipation capacity of buildings considerably. In this study, the effect of dampers on a typical 10-storey reinforced concrete structure with a ductile moment-resisting frame was investigated. In this context, 5 different models were created according to the calculation of the slip load and the positions of the dampers in the structure. Nonlinear time-history analyzes using 11 different earthquake acceleration records were performed on the models using the ETABS program. As a result of the analyses, storey displacements, energy dissipation ratios, drift ratios, storey accelerations, storey shears, and hysteretic curves of the dampers on the first and last storey and overturning moments are presented. In the study, it was determined that friction dampers increased the energy dissipation capacities of all models. In addition, it has been determined that positioning the dampers in the outer region of the structures and taking the base shear as a basis in the slip load calculation will be more effective.

• 한국터널지하공간학회 논문집
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• 제21권6호
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• pp.811-823
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• 2019

최근에는 수직구 구조물 시공방법으로 현장타설 공법 대비 시공속도가 빠르며, 안전하고 경제적인 연속상승 슬립폼 공법이 다수의 현장에 적용되고 있다. 슬립폼 공법으로 시공 가능한 높이는 2.5~4 m/day로 알려져 있는데, 콘크리트 온도가 10~30℃의 범위 밖에서는 강도 변화나 탄성 특성의 변화에 미치는 영향이 크므로 동절기 공사에서는 3 m/day 이상의 시공속도를 내기가 어렵다. 또한, 콘크리트는 수화 작용으로 인해 수화열이 발생하는데, 이는 콘크리트의 온도 균열을 초래한다. 따라서 슬립폼 연속상승시 콘크리트의 온도 제어 양생이 필요하며, 본 연구에서는 히팅 패널 및 시험용 연속상승 장치를 개발하여 반발경도, 초음파 전파시간, 수화열 및 외부온도를 측정하였다. 이를 기반으로 히팅슬립폼을 제작하였으며, "김포 현장"과 "신월 현장"에 히팅슬립폼을 적용하였다. 김포현장은 주간(08:00~17:30) 평균 1.9 m/day 또는 0.200 m/hr, 신월 현장은 2.0 m/day 또는 0.210 m/hr를 목표 상승속도 값으로 비교하였다.

• International Journal of Automotive Technology
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• 제3권4호
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• pp.165-170
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• 2002

For a vehicle Anti-lock Braking System (ABS), the control target is to maintain friction coefficients within maximum range to ensure minimum stopping distance and vehicle stability. But in order to achieve a directionally stable maneuver, tire side forces must be considered along with the braking friction. Focusing on combined braking and turning operation conditions, this paper presents a new control scheme for an ABS controller design, which calculates optimal target wheel slip ratio on-line based on vehicle dynamic states and prevailing road condition. A fuzzy logic approach is applied to maintain the optimal target slip ratio so that the best compromise between braking deceleration, stopping distance and direction stability performances can be obtained for the vehicle. The scheme is implemented using an 8-DOF nonlinear vehicle model and simulation tests were carried out in different conditions. The simulation results show that the proposed scheme is robust and effective. Compared with a fixed-slip ratio scheme, the stopping distance can be decreased with satisfactory directional control performance meanwhile.

• 대한기계학회논문집A
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• 제41권1호
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• pp.63-68
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• 2017

이 논문에서는 열간 사상압연 공정에서 스트립 통판성의 안정성과 판 품질 향상을 위하여 새로운 선진율 학습모델 개발에 관한 연구를 수행한다. 먼저 기존의 선진율 해석모델에 대한 고찰을 통해 스트립 장력, 루퍼 각도 그리고 롤 주속이 선진율 학습에 크게 영향을 미치는 주요 압연 인자들임을 보인다. 두 번째로는 선진율 학습의 주요 압연 인자들을 이용하여 새로운 선진율 학습모델을 도출한 후, 보조변수 규명 알고리즘을 이용하여 이산시간계 학습모델을 규명한다. 끝으로 컴퓨터 시뮬레이션을 통해 이 논문에서 제안한 새로운 학습모델이 기존의 학습모델보다 유용함을 보인다.

• 한국자동차공학회논문집
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• 제3권4호
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• pp.19-29
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• 1995

This paper discusses the stick-slip phenomenon of the driveline system of a vehicle in consideration of friction. Friction is operated on the between of flywheel and clutch disk. The expressions for obtaining the results have been derived from the equation of motion of a three degree of freedom frictional torsion vibration system which is made up driving part(engine, flywheel), driven part(clutch, transmission) and dynamic load part(vehicle body) by applying forth-order Rungekutta method. It was found that the great affect parameters of the stick-slip or stick motion were surface pressure force between flywheel and clutch disk, time decay parameter of surface pressure force and 1st torsional spring constant of clutch disk when driveline system had been affected by friction force. The results of this study can be used as basic design data of the clutch system for the ride quality improvement of a car.

• 소음진동
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• 제11권3호
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• pp.461-470
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• 2001

A friction-type clutch system sometimes generates spick-slip vibration during engagement, which disturbs smooth start of a car and makes a passenger uncomfortable. In this study, the spick-slip vibration in four types of friction couples was investigated at two different engagement conditions respectively of which the amount of slip time and clutch travel was varied. Results are found as follows. First, the vibration increased at the condition of small engine torque and large torque fluctuations due to higher harmonics of engine speed. Second, the friction couple without a pre-damper has advantages of reducing the vibration. This study also suggested an evaluation method of vehicle vibration in the view point of human perception by using the frequency weighting of ISO2631-1.