• 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.

• 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.

• The Journal of Korea Robotics Society
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• v.4 no.3
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• pp.225-232
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• 2009

In the high precision robot systems, the most popular tasks may be handling of micro-scale objects on a surface such as a micromanipulation robot system. In handling of micro-scale objects, the stiction effect becomes a fundamental issue since the micro-contact mechanics dominates the micromanipulation robot system. In the paper, a theoretical non-stick condition derived from the micro-contact mechanics is carried out for the propose of micro-scale object manipulation. To verify the non-stick condition, a micro-manipulation robot system equipped with a high precision stage system and a microscope system is developed. Experimental results show that the proposed non-stick condition guarantees successful micro-scale object manipulation.

• Tribology and Lubricants
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• v.23 no.1
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• pp.9-13
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• 2007

Despite numerous researches on atomic-scale friction have been carried out for understanding the origin of friction, lots of questions about sliding friction still remain. It is known that friction at atomic-scale always shows unique phenomena called 'stick-slips' which reflect atomic lattice of a scanned surface. In this work, experimental study on the effects of system stiffnesses and load on the atomic-scale stick-slip friction of graphite was performed by using an Atomic Force Microscope and various cantilevers/tips. The objective of this research is to figure out the dependency of atomic-scale friction on the nanomechanical properties in sliding contact such as load, stiffness and contact materials systematically. From this work, the experimental observation of transitions in atomic-scale friction from smooth sliding to multiple stick-slips in air was first made, according to the lateral cantilever stiffness and applied normal load. The superlubricity of graphite could be verified from friction vs. load experiments. Based on the results, the relationship between the stickslip behaviors and contact stiffness was carefully discussed in this work. The results or this work indicate that the atomic-scale stick-slip behaviors can be controlled by adjusting the system stiffnesses and contact materials.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.17 no.1
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• pp.58-63
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• 2009

The objective of this study is to analyze customer needs for the configuration of an aircraft cockpit layout of a single piston propeller aircraft. From the result of survey, we figure out the demand of the potential customers. We consider control stick and instrument out of several items to determine which pay for the aircraft or not. We analyze types and features of the aircraft control stick and the instrument which are equipped in the same aircraft in order to figure out what is best needed through a market survey and a questionnaire survey.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.1
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• pp.1-15
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• 1998

Currently, computational analysis is a popular technology in automobile engineering. Finite element analysis is an excellent method for body analysis. For finite element analysis, accurate modeling is very important to obtain precise information. Stick modeling is a convenient way in that it is easy and simple. When a stick model is utilized, the joints are modified in the tuning process. A tuning method for the joint has been developed. The joints are modeled by designated beam elements. An optimization method called "Goal Programming" is employed to impose the target values. With the tuned joints, the entire optimization has been carried out. Using the "Recursive Quadratic Programming" algorithm, the optimization process determines the configuration of the entire structure and sizes of all the sections. For example, the structure of an electrical vehicle is modeled and analyzed by the method. The stick model works well since the structure is made of aluminium frames. Although the example handles an electrical vehicle, this method can be applied to general vehicle structures.

• Tribology and Lubricants
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• v.21 no.1
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• pp.16-20
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• 2005

Friction and wear characteristics between two steel surfaces under fretting condition are investigated experimentally. The fretting damage caused by low-amplitude oscillatory sliding can be classified into three regimes of gross-slip, mixed-slip and partial-slip due to stick-slip phenomenon. One of the most important characteristics of fretting wear is the transition from gross-slip to mixed-slip. This study was focused on getting the degree of stick-slip out of the friction transition under fretting condition. Fretting wear is divided into three conditions of gross-slip/mixed-slip/partial-slip. The criteria for the division are friction and displacement amplitude, wear scar morphology and dissipated energy. In this test, friction force and displacement were measured for detecting the transition from mixed-slip to gross-slip and qualitatively predicting the degree of the wear.

• Journal of Korean Academy of Nursing
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• v.26 no.3
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• pp.605-622
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• 1996

Needle stick injury, in which blood-borne pathogens including Human Immune-Deficiency virus and hepatitis B virus are transmitted, is one of the major occupational hazards that health professionals face everyday. In order to provide basic data for the development of educational programs for health professionals aimed at preventing and effectively managing needle stick injuries, a retrospective descriptive study was carried out .The subjects of the study were 630 health professionals, 499 nurses and 131 physicians, from two university hospitals in Seoul, Korea. Data on episodes of needle stick experiences over the past is months September 1994 through August 1995, were collected between September 1 and 7, 1995. A Questionaire developed by the researcher was used. The frequencies and the percentile score for episodes of needle stick injuries were calculated using the PC-SAS program. The differences and similarities in reference to the structure, career, and specialty variables were analysed by X$^2$-tests. Results are as follows : 1. Of the sample, 521(82.7%) reported a needle stick injury, 33.4% reported 3 or more episodes of needle stick injuries. 2. The needle stick injuries occured in the following processes : process of percutaneous venepuncture for intra-venous injection and infusion(55.3%), medical examination and treatment(48.9%), per-cutaneous venepuncture for blood sampling (46.3%) and intra-muscular injection(42.2%). 3. The study showed that needle stick injuries occured before(19%), during(25%), and after (56%) client treatment. The major causes of needle stick injuries were perceived to be hastiness(82.2%) and carelessness(48.3%). Of these injuries, 91.8% occured in emergency situations. 4. Follow of care for the injury consisted of : treating the injured site immediately using disinfectants(89.7%), reviewing the clinical records of the patient involved(84.2%), immunological investigation for the status of antibodies(11.1%) and self-medication of antibiotics (10.7%). Only 16.3% of the total episodes were founded to have been reported to the administrative unit. 5. The length of clinical experience of the nurses, clinical specialty and length of clinical experience in physicians were found to have influenced the episodes of needle stick injuries ; nurses with less than 1 year and with more than 6 years of clinical experiences had significantly lower levels (X$^2$=25.04, P=.00), surgeons had significantly higher levels (X$^2$=9.89, P=.02) compared to that of internists and interns, higher(X$^2$=4.54, P=.03)than residents.

• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.89-91
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• 2012

The numerical simulation for detonation failure of ammonium nitrate (AN) based non-ideal explosives is carried out with an accurate and state-of-the-art Eulerian method. Detonation failure is readily observed in the rate stick experiments utilizing the AN mixture explosives and the inert confinements of varying thicknesses. The composition of non-ideal explosives and thickness of the confinements influence the characteristics of detonation failure. Calculated results are compared against the experimental data of both unconfined and confined rate stick problems and provide a reliable guideline to establish a fine-tuned chemical kinetic model for detonation failure.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1999.06a
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• pp.207-212
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• 1999

In VEs (virtual environments) such as a CAVE system, there are three important operations : executive command decision, object selection and 3-D (three-dimensional) pointing. It is necessary to implement these operations in VEs intuitively and accessibly. In CAVE, it is possible for examines to walk and change their viewpoints freely. Then, the input devices which have excellent portability and rich expression are desired. Speech input satisfies both requirements. It is, however, very difficult for the speech input to indicate an exact point in 3-D space. Therefore, an extendable virtual stick is employed and it supports speech input. This paper proposes a user friendly interface using speech and a virtual stick in CAVE system. In this paper, several applications appropriate for the proposed interface are developed. Some problems are pointed out from the applications.