• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2737-2742
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• 2003

Kinematic calibration enhances absolute accuracy by compensating for the fabrication tolerances and installation errors. Effectiveness of calibration procedures depends greatly on the measurements performed. While the Cartesian postures are measured completely, all of the geometric parameters can be identified to their true values. With partial pose measurements, however, few geometric parameters may not be identifiable and effectiveness of the calibration results may vary significantly within the workspace. QR decomposition of the identification Jacobian matrix can reveal the non-identifiable parameters. Selecting postures for measurement is also an important issue for efficient calibration procedure. Typically, the condition number of the identification Jacobian is minimized to find optimum postures. This paper investigates identifiable parameters and optimum postures for four different calibration procedures - measuring postures completely with inverse kinematic residuals, measuring postures completely with forward kinematics residuals, measuring only the three position components, and restraining the mobility of the end-effector using a constraint link. The study is performed for a six degree-of-freedom fully parallel HexaSlide type paralle manipulator, HSM. Results verify that all parameters are identifiable with complete posture measurements. For the case of position measurements, one and for the case of constraint link, three parameters were found non-identifiable. Optimal postures showed the same trend of orienting themselves on the boundaries of the search space.

• Journal of Korean Academy of Nursing
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• v.38 no.5
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• pp.676-684
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• 2008

Purpose: The purpose of this study was to identify the risk factors for falls and to suggest data for developing a program for preventing falls. Methods: This was a case-control study in five university hospitals and a general hospital. In total, 216 patients over the age of 18 yr admitted from January 1 to December 31, 2007 participated. One hundred eight patients with experience of falling were matched by gender, age level, diagnosis, and length of stay with 108 patents with no experience of falling admitted on the same unit. A quality assurance coordinator nurse in each hospital examined 35 fall risk factors developed by researchers. Results: In acute hospitals, history of falls, orientation ability, dizziness or vertigo, general weakness, urination problems, transfer/mobility difficulty, walking dependency, impatience, benzodiazepines, diuretics, and vasodilators showed significance on adjusted-odds ratios for fall. Logistic regression analysis was performed to elucidate the factors that influence falls. The probability of falls was increased by dizziness/vertigo, general weakness, and impatience/agitation. Conclusion: This finding can be used as a useful resource in developing nursing intervention programs to predict and prevent the falls of inpatients.

• Journal of the Korea Society of Computer and Information
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• v.22 no.9
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• pp.91-97
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• 2017

IoT (Internet of Things) systems are based on heterogeneous hardware systems of different types of devices interconnected each other, ranging from miniaturized and low-power wireless sensor node to cloud servers. These IoT systems composed of heterogeneous hardware utilize data sets collected from a particular set of sensors or control designated actuators when needed using open APIs created through abstraction of devices' resources associated to service applications. However, previously existing IoT services have been usually developed based on vertical platforms, whose sharing and exchange of data is limited within each industry domain, for example, healthcare. Such problem is called 'data silo', and considered one of crucial issues to be solved for the success of establishing IoT ecosystems. Also, IoT services may need to dynamically organize their services according to the change of status of connected devices due to their mobility and dynamic network connectivity. We propose a way of dynamically composing IoT services under the concept of WoT (Web of Things) where heterogeneous devices across different industries are fully integrated into the Web. Our approach allows developers to create IoT services or mash them up in an efficient way using Web objects registered into multiple standardized horizontal IoT platforms where their resources are discoverable and accessible. A Web-based service composition tool is developed to evaluate the practical feasibility of our approach under real-world service development.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.45 no.6
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• pp.55-59
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• 2008

For effective mobility control of UGV(unmanned ground vehicle), the terrain cover classification is an important component as well as terrain geometry recognition and obstacle detection. The vision based terrain cover classification algorithm consists of pre-processing, feature extraction, classification and post-processing. In this paper, we present a method to classify terrain covers based on the color and texture information. The color space conversion is performed for the pre-processing, the wavelet transform is applied for feature extraction, and the SVM(support vector machine) is applied for the classifier. Experimental results show that the proposed algorithm has a promising classification performance.

• Convergence Security Journal
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• v.11 no.4
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• pp.67-75
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• 2011

Recently, the number of smartphone users is rising rapidly due to an influx of foreign smartphones and sales of domestic products. According to the increase of smartphone users, smartphone malwares are also increasing sharply. Hence it is necessary to protect smartphone against mobile malwares. There are device management protocols as SNMP, TR-069. But these protocols are not suitable for mobile device management because of restrictive management function and unsupported mobility. OMA DM which is a standard for mobile device management has been adopted as mobile device management protocol for most of 2G,3G. Thus it amounts that OMA DM is suitable for smartphone management system. In this paper, the mobile device management system based on OMA DM is designed. This system can remove smartphone malware by remote control.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.12
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• pp.2030-2039
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• 2001

Recently, various inpipe inspection robots are developed and its effective values are increased in industrial use. However, it is so difficult to make a inpipe inspection robot system which has flexible mobility and accuracy of inspection in pipelines. Especially, it is very important to know the exact crack position. In this paper, we are to present a lately developed inpipe inspection robot system which can resolve the above Problems. The robot is configured as an articulated structure like a snake. Two active driving vehicles are located in front and rear of the inspection robot respectively and passive modules such as a nondestructive testing module and a control module are chained between the active vehicles. Special feature of the robot system is a ground interface, which is able to show informations of robot and pipelines. By using this, so called virtual map in this paper, user is able to know the pipelines'feature and crack position.

• Journal of Korea Society of Industrial Information Systems
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• v.7 no.3
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• pp.68-73
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• 2002

This study has been advanced to the design method for embodying the hydraulic circuit and control device in considering the safety for the development of wheelchair lift, using in the public transportation bus. Recently, mobility and accessibility occurs for the elder and the handicapped in the aging problem, In this paper, we design the hydraulic power system to operate lifter loading one wheelchair handicapped person and one's supporter to get in the bus. We develop the lifter safely. We check the trajectories of lifter inside frame box to protect its corrosion and the stress at the joints of mechanical structure. Those can be helped to keep the safety and accuracy of the multiple dynamic systems for precision quality assurance in mass production.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1068-1073
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• 2005

Development of a locomotive mechanism for the capsule type endoscopes will largely enhance the ability to diagnose disease of digestive organs. In connection with it, most of the researches have focused on an installable locomotive mechanism in the capsule. In this paper, it is introduced that the movement of a capsule type endoscope in digestive organ can be manipulated by magnetic force produced outside human body. Since the magnetic force is provided by permanent magnets, no additional power supply to the capsule is required. Using a robotic manipulator for locating the external magnet, the capsule motion control system can cover the whole human digestive organs. This study is particularly concentrated on dither motion effect to improve the mobility of capsule type endoscope. It was experimentally found out that the friction coefficient between the capsule and digestive organ can be remarkably reduced by superposing yawing or rolling dither motion on the translatory motion. In this paper, the experimental results obtained while the direction, amplitude and frequency of sinusoidal dither motion were changed are reported.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.2
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• pp.121-129
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• 2000

The robotic automation in NonDestructive Testing(NDT) is a promising field of research and it helps to expand the applications of NDT enormously. Especially, in the case of pipelines which are widely used in various industrial facilities, it is required to secure adequate ways of inspection in the usual maintenance activitites. In this paper, we present a robot system for inpipe inspection of underground urban gas pipelines. The robot is configured as an articulated structure like a snake with a tether cable. Two active driving vehicles are located in front and rear of the system, respectively and passive modules such as a NonDestructive Testing module and a control module are chained between the active vehicles. The proposed system has outstanding mobility by employing a new steering mechanism called Double Active Universal Joint, which makes it possible to cope with complicated configurations of underground pipelines. Characteristic features of the system are described and the construction of the system is briefly outlined.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.200-200
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• 2003

Polycrystalline Si(polysilicon) TFTs have opened a way for the next generation of display devices, due to their higher mobility of charge carriers relative to a-Si TFTs. The polysilicon W applications extend from the current Liquid Crystal Displays to the next generation Organic Light Emitting Diodes (OLED) displays. In particular, the OLED devices require a stricter control of properties of gate oxide layer, polysilicon layer, and their interface. The polysilicon layer is generally obtained by annealing thin film a-Si layer using techniques such as solid phase crystallization and excimer laser annealing. Typically laser-crystallized Si films have grain sizes of less than 1 micron, and their electrical/dielectric properties are strongly affected by the presence of grain boundaries. Impedance spectroscopy allows the frequency-dependent measurement of impedance and can be applied to inteface-controlled materials, resolving the respective contributions of grain boundaries, interfaces, and/or surface. Impedance spectroscopy was applied to laser-annealed Si thin films, using the electrodes which are designed specially for thin films. In order to understand the effect of grain size on physical properties, the amorphous Si was exposed to different laser energy densities, thereby varying the grain size of the resulting films. The microstructural characterization was carried out to accompany the electrical/dielectric properties obtained using the impedance spectroscopy, The correlation will be made between Si grain size and the corresponding electrical/dielectric properties. The ramifications will be discussed in conjunction with active-matrix thin film transistors for Active Matrix OLED.