• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.79.2-79
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• 2002

1. the principal of a PSD(Position Sensitive Detector) 2. the optical system of the proposed method 3. signal processing 4. experimental result A mechanical engineer experiment on the tension test. In this experiment, they use the extensometer which can measure the extended distance of material. A normal extensometer is the contact type which means that the extensometer should attached to the specimen. It is not convenient to the user. The contacting type can also effect the characteristic of the specimen. So a extensometer is changed from contacting type to non-contacting type. Non-contacting type is not necessary to attach the extensometer to the specimen...

• Journal of Korean Ophthalmic Optics Society
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• v.21 no.3
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• pp.215-225
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• 2016

Purpose: The aim of this study was to figure out how the characteristics of soft contact lens materials and pigmentation affect the adherence of C. albicans on soft contact lenses pre-deposited with tear constituents. Methods: The adherent number of C. albicans on clear soft contact lenses (hereinafter clear lenses) and circle soft contact lenses (hereinafter circle lenses) made of etafilcon A, hilaiflcon B and nelfilcon A, respectively, was measured before and after the deposition of artificial tear. Also, bacteria adherence on lenses were observed by a scanning electron microscope. Results: Adherence of C. albicans was significantly different according to lens materials. The amount of adsorption was not different between clear lenses and circle lenses made of etafilcon A however, the number of bacteria absorption was bigger in hilafilcon B and nelfilcon A lenses. More absorption of C. albicans was found in the non-pigmented central area compared the pigmented area, and non-pigmented peripheral area has more bacterial absorption than non-pigmented central area. The number of C. albicans decreased in the case that tear protein was pre-deposited. The maintenance of antibacterial activity against C. albicans was different according to lens materials thus, etafilcon A has the longest period of its maintenance. Conclusions: It was revealed that the number of C. albicans was different according to the characteristics of lens materials, pigmentation or non-pigmentation, the pigmented area of soft contact lenses. Thus, it is suggested that the management method should be different according to the adsorption characteristics of C. albicans.

• Korean Chemical Engineering Research
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• v.56 no.3
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• pp.327-334
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• 2018

Water-repellent coating solutions were prepared by sol-gel method using tetraethoxysilane (TEOS) and methyltrimethoxysilane (MTMS) as precursors. The solutions were spin-coated on a cold-rolled steel sheet and thermally cured to prepare a non-fluorine water-repellent coating films. The effects of molar ratios of MTMS/TEOS, water concentration and ammonia concentration on the hydrophobic properties of the coating films were studied. The contact angle of water on coating films prepared by varying the molar ratio of MTMS/TEOS to 1~20 showed a maximum value of $108^{\circ}$ when the MTMS/TEOS molar ratio was 10. With increasing water content, the coating films showed the larger contact angles and the better the water repellency. As the amount of ammonia added was increased, the contact angles of coating films were increased, showing the better the water repellency. It is considered that the larger the amount of ammonia added, the larger the size of the silica particles generated, which increases the surface roughness of the silica particles, thereby increasing the water repellency.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.25.2-25.2
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• 2005

• The Journal of Korea Robotics Society
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• v.7 no.3
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• pp.171-181
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• 2012

Outdoor mobile robots are faced with various terrain types having different characteristics. To run safely and carry out the mission, mobile robot should recognize terrain types, physical and geometric characteristics and so on. It is essential to control appropriate motion for each terrain characteristics. One way to determine the terrain types is to use non-contact sensor data such as vision and laser sensor. Another way is to use contact sensor data such as slope of body, vibration and current of motor that are reaction data from the ground to the tire. In this paper, we presented experimental results on terrain classification using contact sensor data. We made a mobile robot for collecting contact sensor data and collected data from four terrains we chose for experimental terrains. Through analysis of the collecting data, we suggested a new method of terrain feature extraction considering physical characteristics and confirmed that the proposed method can classify the four terrains that we chose for experimental terrains. We can also be confirmed that terrain feature extraction method using Fast Fourier Transform (FFT) typically used in previous studies and the proposed method have similar classification performance through back propagation learning algorithm. However, both methods differ in the amount of data including terrain feature information. So we defined an index determined by the amount of terrain feature information and classification error rate. And the index can evaluate classification efficiency. We compared the results of each method through the index. The comparison showed that our method is more efficient than the existing method.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1997.10a
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• pp.87-94
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• 1997

The circular plate resting on Boussinesq's half-space model under axisymmetric loading is studied by a finite element procedure to evaluate the distribution of contact pressure between plate and elastic half-space. The displacement of half-space due to axisymmetric surface loading can be evaluated by double integration of Boussinesq's solution. On that case the analytical integration can be executed for the radial direction but the analytical integration for the circumferential direction is impossible and the numerical integration should be considered. With the radial integration we can get non-dimensional function. Then the numerical integration for the formula is executed for the circumferential direction and the results are approximated 5th order Polynomials by using the least square method. With these 5th order approximate formula, the flexibility matrix of half-space is constructed as the coefficient matrix of nodal contact pressure by the finite element procedures. Iteration procedures are attempted by using this method to determine the separated region.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.494-497
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• 2004

A dynamic simulation for a high-speed pantograph-overheadline has been performed using mode superposition method to predict contact forces between pantograph and overheadline. We can deal with non-linear dampers of the pantograph and pre-sag of overhead-line for the simulation. But, we can not consider slackness of dropper in the overhead-line. According to the simulation results, the contact forces and displacements are reasonably predicted, compared with other foreign simulation results.

• Journal of Powder Materials
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• v.28 no.1
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• pp.1-6
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• 2021

Accurate and effective powder compaction analyses are performed for brittle materials such as graphite, utilized as a solid lubricant, by using the discrete element method (DEM). The reliability of the DEM analysis is confirmed by comparing the results of graphite powder compaction analyses using the DEM particle bonding contact model and particle non-bonding contact model with those from the powder compaction experiment under the same conditions. To improve the characteristics, the parameters influencing the compaction properties of the metal-graphite mixtures are explored. The compressibility increases as the size distribution of the graphite powder increases, where the shape of the graphite particles is uniform. The improved compaction characteristics of the metal-graphite (bonding model) mixtures are further verified by the stress transmission and compressive force distribution between the top and bottom punches. It is confirmed that the application of graphite (bonding model) powders resulted in improved stress transmission and compressive force distribution of 24% and 85%, respectively.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.4
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• pp.403-407
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• 2010

Gecko adhesion system consists of beam-shaped seta and spatula which has the role of adhesive pad. In this paper, adhesion mechanism of gecko adhesion system is performed by using adhesive beam contact model. this model has a feature of non-uniform stress profile on the contact surface and adhesion/detachment mechanism is determined by the tensile stress of the contact region. a spatula tip pad has the role of reduction of maximum tensile stress and adhesive force is increased due to this effect. As for a reverse loading case, maximum compressive stress drops by the spatula effect and this cause unsymmetric loading conditions between adhesion and detachment forces. In this study, finite element method is used for the analysis of adhesive beam contact model and the results for spatula effect are presented.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.4
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• pp.1233-1240
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• 1996

Conventional measurement methods using ultrasonic wave or x-ray, eddy current for non-destructive testing(NDT) in nuclear power plants and other industrial plants have been utilized as the method of contact with objects to be inspected. For this reason these methods require relatively much time and inspection area is limited by the location of probe or film. But holograpic interferometry which is a non-contact optical measurement method using a coherent light source has an advantage that quantative measurement can be performed at a time. In this paper a new method using realtime holographic interfreometry and image processing for detecting internal flaws of pressure vessels is presented.