• Journal of Industrial Technology
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• v.24 no.B
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• pp.207-214
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• 2004

An active stick which supplies force feedback to the operator is developed in this study. A mathematical model of the active stick is derived, and compared with the experimental result. It turns out that the frictional torque due to the mechanical contacts of several parts of the stick is one of the major barriers to achieve high precision operation of the stick. The frictional effect of the stick is cancelled out by using a friction observer. The efficacy of the friction observer is verified through the numerical simulation. Because of the observer dynamics, there are some limitations in exact recovering the static friction and Stribeck effect. However, the friction observer follows the real friction on the average. It's anticipated that the application of the friction observer to the closed loop control of the active stick improves the performance of the displacement versus force characteristics, which will be proved experimentally in the further study.

• The Korean Nurse
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• v.34 no.2
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• pp.45-57
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• 1995

A study .to identify an occupational hazards for hospital working health care providers from needle stick injury as an occupational hazards of health care providers in hospital and prevention A survey of 2430 health professionals (2184 nurses, 182 doctors, and 64 Lab technicians) was conducted to describe and provide information about 1) the experience of needle stick. 2) the number of needle stick, 3) the treatment after needle stick. 3) the situation of needle stick, 4) the report of needle stick, 5) the cause of needle stick, 6) the discard method of used needles, and 7) how to worry about getting infection disease after needle stick. Data were collected using questionnarires constructed by the authors and tested by a pilot study. Results of the study showed that 96.7% of the sample had an experience of needle stick (96.8% of the nurses, 96.7% of the doctors, and 92.2% of Lab technicians). Seventy seven percent of the sample experienced less than 10 needle sticks, 19% of the sample experienced 11 to 20 needle sticks, and the rest of the sample experienced more than 20 needle sticks. The situations where needle sticks occurred include intrvenous injection (36.5%), intramuscular injection (21.6%), blood withdraw (17.8%), and preparation(11.8%). The study showed that needle sticks (67.5%) usually occurred after client treatment. Health professionals used recapping method (55%) after they used needles. Needle sticks were predominantly caused by the carelessness of health professionals (61%), After needle sticks, 88.2% of the sample subjects treated needle sticks using disinfection technique by themselves. Most of health professionals (92.6%) did not report the accident. and 95.6% of them did not receive any test or further treatment. After needle sticks, 87.8% of nurses, 83.6% of doctors, and 96.6% of lab technicians worried about hepatitis infection. 'Health professionals also worried about AIDS infection, tetanus, venereal infection, and skin injury. These findings suggest that health professionals are at high-risk of needle stick and fail to report needle stick accidents. They should pay more attention to needle stick in order to avoid unwanted infection.

• Tribology and Lubricants
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• v.18 no.1
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• pp.55-60
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• 2002

In many dynamic systems, there are unwanted oscillation which may arise the reduction of performance. Especially in low sliding speed condition, the stick-slip is an important issue because it because unstable motion as well as inaccurate position control in the system. Most previous works on the stick-slip are, however, only concerned with simple modeling under the condition of constant normal force. The normal force and the amount of hydraulic oil are variable with a cylinder stroke in the telescopic boom. This paper presents the pressure variations during stick-slip with the cylinder of telescope boom. Pressure variations by stick-slip has a similar pattern to that of single mass-spring model. The stick-slip is gradually decreased by means of increased flow rate.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.118-121
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• 2006

Stick-slip of belt-pulley system produces vibration which results in the noise problem. Experimental study was carried out to investigate the phenomenon of stick-slip with simple v-belt system. The optical displacement sensor detected the vibration caused by the stick-slip of which the frequency was significantly dependant on tension of the belt. The rotation speed of putties also affected the frequency and magnitude of the stick-slip vibration. Existence of misalignment between the driven and drive pulleys made some difference in the stick-slip frequency, but not much. Further study is necessary to identify the generation of noise from the stick-slip vibration.

• Proceeding of EDISON Challenge
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• 2015.03a
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• pp.467-475
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• 2015

In this paper, the FREECAD 0.14 was used for modeling conventional Selfie-stick and the newly proposed Selfie-stick design. The purpose of this paper is to demonstrate the utility of FREECAD 0.14, which is open-source and still in development for further use. After modeling the conventional Selfie-stick, CatiyaV5 was used to assemble FREECAD 0.14 drawn elements. Main advance in newly designed Selfie-stick is the portability. To improve portability of the Selfie-stick, folding mechanism was adopted from folding LED stands. Several mechanisms were adopted to improve user convenience as well. Ansys 14.0 was used for structural analyses of conventional Selfie-stick model and the newly designed model as well. Several simplifications for the models were needed to process the analyses. When analyzing the newly designed model various materials were used one by one to find compatible composition. Using Aluminum alloys for the stick and the hand grip was found to be compatible. FREECAD was useful for suggestion of the newly designed model but not so much useful to design an actual product. Various efforts would make FREECAD the best choice for industrial use for free as it is named.

• The Journal of the Acoustical Society of Korea
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• v.43 no.1
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• pp.49-59
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• 2024

Recently, the electric vehicle market is gradually growing due to strengthened environmental regulations and high oil prices. also, in internal combustion engine vehicles, the sensitivity of Buzz, Squeak, Rattle (BSR) noise is increasing as engine Noise, Vibration, and Harshness (NVH)-related noise is reduced and technology for shielding noise coming from outside is developed. In this study, the stick-slip noise that occurs in Panoramic Curved Display (PCD) of automobile was analyzed for the correlation between the surface energy of polymer plastic and the polar component. For polar polymer materials, Acrylonitrile Butadiene Styrene (ABS) and PolyCarbonate-Acrylonitrile Butadiene Styrene (PC-ABS), compound materials were fabricated and evaluated. As a result, when the polar component of the polymer plastic was 3.86 mN/m or higher, stick-slip motion occurred, and as the absolute transition slope increased in the friction behavior over time, the possibility of stick-slip noise increased and the value of the friction coefficient The greater the difference, the greater the strength of the stick-slip noise.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.05a
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• pp.296-303
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• 2002

Tribology, in other words, interacting surfaces in relative motion, is essential in life. The relative motion on surfaces may cause some problems with heat, vibration, noise, and so on. Unwanted vibrations by friction, which may arise during the operation of machines, are costly in terms of reduction of performance and service life. All these phenomena inolve stick-slip. The telescopic boom operations involves stick-slip oscillations like slideways. Unwanted stick-slip oscillations on telescopic boom operations cannot achieve smooth sliding and many developers of that machine makes a lot of effort to remove or reduce it. So this paper presents stick-slip oscillation with pressure of the hydraulic cylinder which drives booms, and attempts a theoretical approach for the numerical analysis for its stick-slip condition.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.371-376
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• 1999

Stick-slip friction is present to some degree in almost all actuators and mechanisms and is often responsible for performance limitations. Simulation of stick-slip friction is difficult because of strongly nonlinear behavior in the vicinity of zero velocity. A straightforward method for representing and simulating friction effects is presented. True zero velocity sticking is represented without equation reformulation or the introduction of numerical stiffness problems. Stick-slip motion is investigated experimentally, and the fundamental characteristics of the stick-slip motion are clarified. Based on these experimental results, the characteristics of static in the period of stick and kinetic friction in the period of slip are studied concretely so as to clarify the stick-slip process.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.90.6-90
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• 2002

An active stick which has the variable force-feel characteristics is developed. A combined position and force control strategy is mechanized using a 2-axis built-in force sensor and LVDT. The 2-axis force sensor which measures the stick force felt by the operator is developed by using strain gages and appropriate instrumental amplifiers. A mathematical model of the active stick dynamics is derived, and compared with the experimental results. The frictional torque of the stick due to the mechanical contacts of several parts makes the experimental frequency responses to be dependent on the magnitude of excitation signal, and the precision closed loop control to be difficult. A friction observe...

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.250-251
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• 2014

This paper investigates the stick-slip phenomena on spinning shaft. The modeling of the shaft is considered only torsional direction with nonlinear friction. The friction is adopted a negative friction-velocity slope. Based on the model, a nonlinear equation of motion is derived and analyze the stick-slip phenomena. In order to analyze the time dependent response, the nonlinear formulations are numerically solved by nonlinear Newmark method. The numerical results reveal the stick-slip phenomena on the spinning shaft system.