A TMO-based flight program of an unmanned helicopter

Kim, Jungguk,Budiyono, Agus,Kim, Dong-Min,Song, Ho-Geun,Kim, Doo-Hyun Emerald Group Publishing Limited 2011 Aircraft engineering and aerospace technology Vol.83 No.6

<B>Purpose</B> - The purpose of this paper is to introduce a new danger-aware Operational Flight Program (OFP) for the unmanned helicopter's auto-navigation based on the well-known time-triggered message-triggered object (TMO) model. <B>Design/methodology/approach</B> - In this design with the TMO, the danger-awareness means two things. First, an unmanned helicopter maneuvers on safe altitudes to avoid buildings or mountains when navigating to the target position. It is assumed that minimum safe altitudes are given on evenly spaced grids and on the center points of every four adjacent grids. A three-dimensional (3D) path-finding algorithm using this safe-altitude information is proposed. Second, a helicopter automatically avoids a zone with very high temperature caused by a fire. <B>Findings</B> - Since the auto-flight control system requires componentized real-time processing of sensors and controllers, the TMO model that has periodic and sporadic threads as members, has been used in designing the OFP. It has been found that using the TMO scheme is a way to construct a very flexible, well-componentized and timeliness-guaranteed OFP. <B>Practical implications</B> - As the RTOS, RT-eCos has been used. It was developed a few years ago based on the eCos3.0 to support the real-time thread model of the TMO scheme. To verify this navigation system, a hardware-in-the-loop simulation (HILS) system also has been developed. <B>Originality/value</B> - Designing an OFP by using the real-time object model TMO and the proposed 3D safe path finding algorithm is a whole new effective deadline-based approach. And the developed OFP can be used intensively in the phase of disaster response and recovery.

Application of a low-glitch current cell in 10-bit CMOS current-steering DAC

Cui, Zhi-Yuan,Choi, Joong-Ho,Kim, Yeong-Seuk,Kim, Shi-Ho,Kim, Nam-Soo Emerald Group Publishing Limited 2009 Microelectronics international Vol.26 No.3

<B>Purpose</B> - The purpose of this paper is to describe the application of low-glitch current cell in a digital to analog converter (DAC) to reduce the clock-feedthrough effect and achieve a low power consumption. <B>Design/methodology/approach</B> - A low-glitch current switch cell is applied in a ten-bit two-stage DAC which is composed of a unary cell matrix for six most significant bits and a binary weighted array for four least significant bits (LSBs). The current cell is composed of four transistors to neutralize the clock-feedthrough effect and it enables DAC to operate in good linearity and low power consumption. The prototype DAC is being implemented in a 0.35µm complementary metal-oxide semiconductor process. The reduction in glitch energy and power consumption has been realized by preliminary experiment and simulation. <B>Findings</B> - Compared to conventional current cell, more than 15 per cent reduction of glitch energy has been obtained in this work. The DAC is estimated that differential nonlinearity is within 0.1 LSB and the maximum power consumption is 68?mW at the sampling frequency of 100?MHz. <B>Originality/value</B> - Comparison with other conventional work indicates that the current cell proposed in this paper shows much better performance in terms of switching spike and glitch, which may come from the extra dummy transistor in cell and reduce the clock-feedthrough effect.

Cooperative robotic assistant with drill-by-wire end-effector for spinal fusion surgery

Lee, Jongwon,Hwang, Inwook,Kim, Keehoon,Choi, Seungmoon,Chung, Wan Kyun,Kim, Young Soo Emerald Group Publishing Limited 2009 The Industrial robot Vol.36 No.1

<B>Purpose</B> - The purpose of this paper is to present a surgical robot for spinal fusion and its control framework that provides higher operation accuracy, greater flexibility of robot position control, and improved ergonomics. <B>Design/methodology/approach</B> - A human-guided robot for the spinal fusion surgery has been developed with a dexterous end-effector that is capable of high-speed drilling for cortical layer gimleting and tele-operated insertion of screws into the vertebrae. The end-effector is position-controlled by a five degrees-of-freedom robot body that has a kinematically closed structure to withstand strong reaction force occurring in the surgery. The robot also allows the surgeon to control cooperatively the position and orientation of the end-effector in order to provide maximum flexibility in exploiting his or her expertise. Also incorporated for improved safety is a "drill-by-wire" mechanism wherein a screw is tele-drilled by the surgeon in a mechanically decoupled master/slave system. Finally, a torque-rendering algorithm that adds synthetic open-loop high-frequency components on feedback torque increases the realism of tele-drilling in the screw-by-wire mechanism. <B>Findings</B> - Experimental results indicated that this assistive robot for spinal fusion performs drilling tasks within the static regulation errors less than 0.1?<I>µ</I>m for position control and less than 0.05° for orientation control. The users of the tele-drilling reported subjectively that they experienced torque feedback similar to that of direct screw insertion. <B>Research limitations/implications</B> - Although the robotic surgery system itself has been developed, integration with surgery planning and tracking systems is ongoing. Thus, the screw insertion accuracy of a whole surgery system with the assistive robot is to be investigated in the near future. <B>Originality/value</B> - The paper arguably pioneers the dexterous end-effector appropriately designed for spinal fusion, the cooperative robot position-control algorithm, the screw-by-wire mechanism for indirect screw insertion, and the torque-rendering algorithm for more realistic torque feedback. In particular, the system has the potential of circumventing the screw-loosening problem, a common defect in the conventional surgeon-operated or robot-assisted spinal fusion surgery.

Use of infrared light reflecting landmarks for localization

Emerald Group Publishing Limited 2009 The Industrial robot Vol.36 No.2

<B>Purpose</B> - This paper aims to present a novel localization scheme using infrared light reflecting artificial landmarks. <B>Design/methodology/approach</B> - By putting the infrared light reflecting landmarks on the ceiling, localization is achieved. The landmark is designed for effective recognition and identification. From the difference of two successive images, one with the infrared light illumination and the other without, the landmarks are clearly identified. <B>Findings</B> - From the mathematical analysis, a greater of landmarks are required if the robot's tilt angles are not known. With the camera's pan/tilt angles information, the distortion of the image can be corrected and fewer landmarks are required. Movement of the camera while getting two successive images is modeled and is compensated. <B>Originality/value</B> - Thorough analysis of practical issues such as capturing the image from a non-flat floor, pan/tilt motion of the camera and movement of the camera is presented.

Cure depth control for complex 3D microstructure fabrication in dynamic mask projection microstereolithography

Choi, Jae-Won,Wicker, Ryan B.,Cho, Seok-Hyun,Ha, Chang-Sik,Lee, Seok-Hee Emerald Group Publishing Limited 2009 RAPID PROTOTYPING JOURNAL Vol.15 No.1

<B>Purpose</B> - The paper's aim is to explore a method using light absorption for improving manufacturing of complex, three-dimensional (3D) micro-parts with a previously developed dynamic mask projection microstereolithography (MSL) system. A common issue with stereolithography systems and especially important in MSL is uncontrolled penetration of the ultraviolet light source into the photocrosslinkable resin when fabricating down-facing surfaces. To accurately fabricate complex 3D parts with down-facing surfaces, a chemical light absorber, Tinuvin 327™ was mixed in different concentrations into an acrylate-based photocurable resin, and the solutions were tested for cure depths and successful micro-part fabrication. <B>Design/methodology/approach</B> - Tinuvin 327 was selected as the light absorber based on its high absorption characteristics (~0.4) at 365?nm (the filtered light wavelength used in the MSL system). Four concentrations of Tinuvin 327 in resin were used (0.00, 0.05, 0.10, and 0.15 percent (w/w)), and cure depth experiments were performed. To investigate the effects of different concentrations of Tinuvin 327 on complex 3D microstructure fabrication, several microstructures with overhanging features such as a fan and spring were fabricated. <B>Findings</B> - Results showed that higher concentrations of Tinuvin 327 reduced penetration depths and thus cure depths. For the resin with 0.15 percent (w/w) of the Tinuvin 327, a cure depth of ~30?µm was achieved as compared to ~200?µm without the light absorber. The four resin solutions were used to fabricate complex 3D microstructures, and different concentrations of Tinuvin 327 at a given irradiance and exposure energy were required for successful fabrication depending on the geometry of the micro-part (concentrations of 0.05 and 0.1 percent (w/w) provided the most accurate builds for the fan and spring, respectively). <B>Research limitations/implications</B> - Although two different concentrations of light absorber in solution were required to demonstrate successful fabrication for two different micro-part geometries (a fan and spring), the experiments were performed using a single irradiance and exposure energy. A single solution with the light absorber could have possibly been used to fabricate these micro-parts by varying irradiance and/or exposure energy, although the effects of varying these parameters on geometric accuracy, mechanical strength, overall manufacturing time, and other variables were not explored. <B>Originality/value</B> - This work systematically investigated 3D microstructure fabrication using different concentrations of a light absorber in solution, and demonstrated that different light absorption characteristics were required for different down-facing micro-features.

Optimum design of Maglev lift system's electromagnet for weight reduction using response surface methodology

Hong, Do-Kwan,Kim, Jong-Moon Emerald Group Publishing Limited 2008 Compel Vol.27 No.4

<B>Purpose</B> - This paper aims to discuss the optimum design of a Maglev lift system's electromagnet to reduce the weight of the machine with constraint of normal force using response surface methodology (RSM). <B>Design/methodology/approach</B> - The optimum design of Maglev lift system's electromagnet for weight reduction is performed by using RSM. The magnetostatic analysis of Maglev lift system's electromagnet is performed by using ANSYS. <B>Findings</B> - The process is based on minimization of an appropriate objective function, while at each step the response is determined by the 3D finite element method (FEM). <B>Research limitations/implications</B> - It is necessary to compare normal force between the 3D FEM result and the experimental result of the manufactured model. <B>Originality/value</B> - The paper deals with the possibility of using the RSM for optimization of an electromagnet with a higher number of the design variables.

Analysis of online social networks: a cross-national study

Emerald Group Publishing Limited 2010 ONLINE INFORMATION REVIEW Vol.34 No.3

<B>Purpose</B> - The purpose of this study is to investigate users' underlying motivations for engaging in social networking through online social networking services (SNS) compared with their behaviour. It seeks to examine the differences between USA, and Korean users. <B>Design/methodology/approach</B> - The study surveyed SNS users in the USA and Korea to determine the key differences between the two countries. Survey questions, developed in English and Korean, were presented in each country to explore the influences of various factors from the modified Technology Acceptance Model on SNS user dimensions. The analytic design methods were based on structural equation modelling and applied to the data gathered. The TAM factors of SNS were analysed, focusing on the differences in motives between the two countries. <B>Findings</B> - The results of the online survey of SNS users validated the proposed theoretical model's ability to explain and predict user acceptance of SNS very well. While the results illustrate the importance of both extrinsic and intrinsic motivation, the two countries showed different sets of motivations, providing useful implications for theory and practice. <B>Practical implications</B> - Based on the results of the study, practical applications for marketing strategies in online SNS markets and theoretical applications for cross-national studies are recommended. <B>Originality/value</B> - Despite the burgeoning interest in SNS, only a few studies have explored the acceptance of SNS in a cross-national manner, leading to a paucity of information on how different cultures influence acceptance of online services.

Document delivery through domestic and international collaborations: the KISTI practice

Emerald Group Publishing Limited 2010 Interlending & document supply Vol.38 No.3

<B>Purpose</B> - The purpose of this article is to introduce the KISTI document delivery service, to describe its collaboration with national and international institutions, and to explore the way KISTI develops and extends international cooperation. <B>Design/methodology/approach</B> - The article describes the work of KISTI and draws on the transaction data of documents delivered by KISTI. <B>Findings</B> - Resource sharing through national and international cooperation is becoming of increasing importance in Korea. KISTI operates its document delivery service at three levels: inNIDS, netNIDS, and globalNIDS. KISTI is the focal point in Korea for the delivery of domestic knowledge to other countries. <B>Originality/value</B> - One of the few articles to deal in detail with the services provided by KISTI - the Korean global document delivery service.

An exploratory study of the weather and calendar effects on tourism web site usage

Lim, Gyoo Gun,Kim, Do Hyun,Choi, Minnseok,Choi, Jin H.,Lee, Kun Chang Emerald Group Publishing Limited 2010 ONLINE INFORMATION REVIEW Vol.34 No.1

<B>Purpose</B> - The purpose of this paper is to investigate the weather and calendar effects on the usage pattern of a tourism web site. <B>Design/methodology/approach</B> - This paper analyses data from a yearlong web log involving 21,655,089 visitors to a popular tourism web site. The weather factors include rain, snow, cloud cover, and the calendar factors include seasons and holidays in order to test the proposed model. <B>Findings</B> - Using data from the Korea Tourism Organisation and the Korean Meteorological Administration, the results show that when it was rainy, cloudy, summer or a workday, the number of visitors to the tourism information web site was higher. <B>Originality/value</B> - The results provide managers involved in the tourism industry with useful insights for effective use of web sites by running them more efficiently and setting up appropriate marketing strategies in terms of the weather and calendar variables.

Utilization of color change in the condition monitoring of synthetic hydraulic oils

Ossia, Chinwuba Victor,Hosung, Kong,Markova, Lyiubov V. Emerald Group Publishing Limited 2010 Industrial lubrication and tribology Vol.62 No.6

<B>Purpose</B> - The purpose of this paper is to present an optical technique for the condition monitoring of synthetic hydraulic oil; a deviation from the current techniques based on electrical principles which could be masked by wear particles and polar contaminants in oil. <B>Design/methodology/approach</B> - Color-change detecting device was developed using light-emitting diodes, optic fibers and photodiodes of three-color-sensing elements. Color ratio (CR) and total contamination parameters based on transmitted light intensity in red, green, and blue wavelengths were used for oil chemical and particulate contamination assessment. <B>Findings</B> - CR criterion was found independent of the particulate contamination of oil; but depended on chemical degradation. Total contamination index of the device depended on both the chemical degradation and particulate contamination of the oil, being most sensitive in blue wavelength, and least in the red. Test results for synthetic hydraulic oils monitored corroborated with results of viscosity, total acid number, RDE emission spectrometry, particulate counts and UV-Vis photospectrometry. CR showed a clearer indication of oil degradation, compared to key monitoring parameters such as total acid number, viscosity, RDE emission spectrometry and particle counts. <B>Originality/value</B> - This paper demonstrates how oil chemical degradation and total contamination could be detected through the device, before incipient wear occurs at tribological interfaces. The results showed that the color-change parameters are effective criteria for the condition monitoring of synthetic hydraulic oils.