• Journal of Mechanical Science and Technology
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• v.16 no.3
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• pp.283-291
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• 2002

The paper demonstrates the tracking performance of a sliding horizon feedback/feedforward preview optimal control when applied to a hydraulic motion simulator which has been built to provide a means of replicating the actual ride dynamics of an automobile seat/human system. The design was developed by solving an ordinary differential equation problem instead of a Ricatti equation. Simulation results indicate that the proposed technique has good performance improvement in phase tracking when compared to the classical design methods. It is also found that the controller can be adjusted more easily for robustness due to more tuning parameters.

• Smart Structures and Systems
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• v.1 no.2
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• pp.159-184
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• 2005

The paper intends to summarize some guidelines for future smart structure system application in military aircraft. This preview of system integration is based upon a review on approximately one and a half decades of application oriented aerospace related smart structures research. Achievements in the area of structural health monitoring, adaptive shape, adaptive load bearing devices and active vibration control have been reached, potentials have been identified, several feasibility studies have been performed and some smart technologies have been already implemented. However the realization of anticipated visions and previously initial timescales announced have been rather too optimistic. The current development shall be based on a more realistic basis including more emphasis on fundamental aircraft strength, stiffness, static and dynamic load and stability requirements of aircraft and interdisciplinary integration requirements and improvements of integrated actors, actuator systems and control systems including micro controllers.

• International Journal of Automotive Technology
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• v.5 no.2
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• pp.77-88
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• 2004

Narrow commuter vehicles can address many congestion, parking and pollution issues associated with urban transportation. In making narrow vehicles safe, comfortable and acceptable to the public, active tilt control systems are likely to playa crucial role. This paper focuses on the development of an active direct tilt control system for a narrow vehicle that utilizes an actuator in the vehicle suspension. A simple PD controller can stabilize the tilt dynamics of the vehicle to any desired tilt angle. However, the challenges in the tilt control system design arise in determining the desired lean angle in real-time and in minimizing tilt actuator torque requirements. Minimizing torque requirements requires the tilting and turning of the vehicle to be synchronized as closely as possible. This paper explores two different control design approaches to meet these challenges. A Receding Horizon Controller (RHC) is first developed so as to systematically incorporate preview on road curvature and synchronize tilting with driver initiated turning. Second, a nonlinear control system that utilizes feedback linearization is developed and found to be effective in reducing torque. A close analysis of the complex feedback linearization controller provides insight into which terms are important for reducing actuator effort. This is used to reduce controller complexity and obtain a simple nonlinear controller that provides good performance.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.1
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• pp.249-256
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• 2012

ePUB is one of the most pervasive eBook formats since it was announced as a 2009 standard in IDPF(International Digital Publishing Forum). ePUB is compressed as a ZIP Archive format and structured as a standard format of OCF. Domestically and internationally, eBook services applying DRM into ePUB have currently been active, while it does not satisfy various needs from business because it does not support preview service which is due to the encryption of the whole ePUB as a single key. This study suggests a way to apply diverse business models by providing eBook content based on ePUB multiple key encryption method, not by encrypting it simply as a single key. The encryption method which applies a multiple key encryption method is suggested as a practically appliable form together with licence issuing and delivery method and decryption method in eBook readers. The multiple key encryption method suggested in this study will make it possible to support partial preview services of ePUB based eBook content. It will be applied to diverse service models and enhance the security level better then single key based encryption method.

• International Journal of Highway Engineering
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• v.14 no.1
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• pp.9-16
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• 2012

The performance of road markings is classified into the visibility at daytime, night time, wet condition and rainy conditions. The objective of this study is to obtain the driving safety of drivers under conditions of unstable weather condition such as the rain. The visibility of road markings is closely related to the preview time and detection distances and the ways to improve road marking materials and increase the dry retroreflectivity and wet retroreflectivity, which are the measures of daytime and nighttime visibility is researched to decrease the traffic accidents. For this purpose, Road marking glass beads with the refraction rate of 1.5 and 2.2 are introduced to raise the retroreflectivity. After investigating the minimum threshold retroreflectivity and Install Minimum retroreflectivity at home and abroad, minimum control values for the roadmarking visibility and improvement of nightime rainy retroreflectivity are suggested by physical properties and retroreflectivity experiments.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.3
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• pp.603-610
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• 1998

This paper develops a 7 DOF vehicle model to study the effects of the active suspension on ride. The model is used to derive a control law for the active suspension using a full state linear optimal control technique. A wheelbase preview type active suspension is also considered in the control law derivation. The time delay between wheelbases is approximated using Pade approximation technique. The ride model is extended to a 14 DOF handling model. The 14 DOF handling model includes lateral, longitudinal, yaw and four wheel spin motions in addition to the 7 DOF ride model. A control law which is derived considering only ride related parameters is used to study the effects of the active suspension on a vehicle handling. J-turn maneuver simulation results show that the active suspension has a slower response in lateral acceleration and yaw rate, a bigger steady state lateral acceleration and an oversteer tendency. Lane changing maneuver simulation results show that the active suspension has a little bigger lateral acceleration but a much smaller roll angle and roll motion. Braking maneuver simulation results show that the active suspension has a much smaller pitch angle and pitch motion.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.7
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• pp.599-605
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• 2017

For an unmanned vehicle to be driven on the off-road terrain, it is necessary to consider the vehicle's stability. This paper suggests a path tracking controller for simulation of real-time vehicle stability analysis. The path tracking controller uses the preview distance to track the given trajectory. The disturbance moment is estimated using the yaw moment observer, and this information is used for compensation in the yaw moment control. On a curved path, the vehicle's desired velocity is determined from the curvature of the path. Because the vehicle is equipped with six independent motor driven wheels, the driving torques are distributed on all the wheels. The effectiveness of the path tracking controller is verified using ADAMS/MATLAB co-simulation.

• Journal of the Korean Society of Clothing and Textiles
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• v.24 no.7
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• pp.995-1003
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• 2000

This study examined the role of apparel merchandisers’in Korea. Data were collected by interviewing 7 apparel merchandisers who had worked for major apparel manufacturers. The interviews were analyzed by use of chronologically sequenced events. Korean apparel merchandisers take part in planning and production of the merchandise, sales management, and promotion. Merchandisers’activities related to merchandise planning were as follows: analysis of fashion trend and market, concept evolvement, planning of assortment and volume assortment, time table set up, color pallette decision, fabrication, line adoption, pricing, line preview, production planning, and placing order of materials. Merchandisers’activities related to apparel production were planning and controlling production and consolidation. In sales, merchandisers analyze retail sales and control inventory by reorder or conducting markdown sale. In relation to promotion, apparel merchandisers monitor merchandise advertisement, and educate salesman.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.323-327
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• 1996

Gap and thickness difference information between blanks are often necessary for tailored blank welding quality evaluation , optimum welding parameters selection and evaluation of shearing machine, blink allocation device accuracy and clamping device. We develope 3D vision system and camera unit using structured lighting for this purpose. A simple ar d efficient scheme for gap and thickness feature recognition Is developed as well as measurements. Experimental results shows this system measuring accuracy is 10 ${\mu}{\textrm}{m}$ and 16${\mu}{\textrm}{m}$ for gap and thickness difference respectively The data are expexed to be useful for preview gap control.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.12
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• pp.17-23
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• 1997

A 3-D vision system is developed to evaluate blanks' line up and monitor gap and thickness difference between blanks in tailored blank welding system. A structured lighting method is used for 3-D vision recognition. Images of sheared portion in blanks are irregular according to roughness of blank surface, shape of sheared geometry and blurring. It is difficult to get accurate and reliable informations in the case of using binary image processing or contour detection techniques in real time for such images. We propoe a new energy integration method robust to blurring and changes of illumination. The method is computationally simple, and uses feature restoration concept, different to another digital image restoration methods which aim image itself restoration and may be used in conventional applications using structured line lighting technique. Experimental results show this system measuring repeatability is .+-. pixel for gap and thickness difference in static and dynamic tests. The data are expected to be useful for preview gap control.