• Journal of Mechanical Science and Technology
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• v.14 no.5
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• pp.508-517
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• 2000

For shift quality improvement, torque sensors are currently too expensive to be used on production vehicles. To achieve smooth acceleration shift, the reference trajectory of the clutch slip speed for accomplishing the shift process within a designated shift completion time and its relationship with the clutch actuating torque were suggested by Jeong and Lee (1999). In order to facilitate the proposed algorithm, nonlinear estimators for necessary information such as the axle shaft torque, clutch friction and turbine torque were designed using only speed sensors. Accounting for the modeling error, a control law for this indirect smooth shift was proposed based on the above mentioned suggestions. Simulation results of the proposed estimators and shift controller were presented and further considerations for practical applications are discussed.

• Journal of Power Electronics
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• v.16 no.3
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• pp.1025-1035
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• 2016

Luenberger observer (LO)-based sensorless multi-loop control of a converter requires an iterative trial-and-error design process, considering that many parameters should be determined, and loop gains are indirectly related to the closed-loop characteristics. Robust H∞ control adopts a compact sensorless controller. The algebraic Riccati equation (ARE)-based and linear matrix inequality (LMI)-based H∞ approaches need an exhaustive procedure, particularly for a low-order controller. Therefore, in this study, a novel robust H∞ synthesis approach is proposed to design a low-order sensorless controller for boost converters, which need not solve any ARE or LMI, and to parameterize the controller by an adjustable parameter behaving like a "knob" on the closed-loop characteristics. Simulation results show the straightforward closed-loop characteristics evaluation and better dynamic performance by the proposed H∞ approach, compared with the LO-based sensorless multi-loop control. Practical experiments on a digital processor confirmed the simulation results.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.1
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• pp.174-184
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• 1997

This paper presents a robust force tracking control of a smart flexible gripper featured by a piezoceramic actuator characterizing its durability and quick response time. A mathematical governing equation for the proposed gripper structure is derived by employing Hamilton's principle and a state space control model is subsequently obtained through model analysis. Uncertain system parameters such as frequency variation are included in the control model. A sliding mode control theory which has inherent robustness to the sys- tem uncertainties is adopted to design a force tracking controller for the piezoceramic actuator. Using out- put information from the tip force sensor, a full-order observer is constructed to estimate state variables of the system. Force tracking performances for desired trajectories represented by sinusoidal and step func- tions are evaluated by undertaking both simulation and experimental works. In addition, in order to illustrate practical feasibility of the proposed method, a two-fingered gripper is constructed and its performance is demonstrated by showing a capability of holding an object.

• Journal of the Korean Society of Clothing and Textiles
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• v.40 no.4
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• pp.746-762
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• 2016

This study considers expression techniques and aesthetic values in the images of head dress reflected in a natural motif. The conclusions of the study are as follows. The first type is the realistic expression (52.4%) such as the reproduction of a natural object's essential form (27.0%), the partial derivation of the natural object (19.3%), and the planarization for the actual image of the natural object (6.1%). The second type is a metaphorical expression (39.0%) which emphasizes the morphological characteristics of nature (18.2%), the structuration of the natural object's silhouette into a three-dimensional or two-dimensional form (11.5%), and the abstract expression of the form in the natural object (9.3%). The third type is a hybrid expression (8.6%) that is a compromise between practical (or metaphorical expressions) so that expression techniques represent a compromise between the natural object's essential form and abstract expression (4.6%) or the combination of the natural object's silhouette into a three-dimensional or a two-dimensional visualization (4.0%). Aesthetic head dress values reflected in the natural motif first indicate a primitive value. This state of natural instinct recreates the natural object or combines part of the biological elements of the natural object to create an inducement to escape from the practical world. The second is amusement in the expression of animals in dynamic and humorous forms creates an illusion of animals being alive with a representative playful enjoyment. The third is abstraction that grant freedom in the observer's aesthetic rational through a reinterpretation of the fashion designer. The fourth is eclecticism where a compromise represents an act of mixing a variety of independent factors to create harmony with the imagery of nature created through the grafting of diverse expression techniques that break away from stereotypes of existing natural objects to create a type of nature that cultivates new values.

• Science of Emotion and Sensibility
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• v.9 no.spc3
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• pp.187-196
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• 2006

This study has showed verified results on 'Survey into Observer Preference for Table Decoration for Eating and Drinking'. It is a preliminary study to look into interrelation of preference to color tables, image adjectives, aesthetic value, by giving color changes in a certain regularity to each influential factor in functional table decoration. The result has demonstrated that, as for color image and preference,'observers prefers mid/low dark-toned brown which gives a feeling of 'high-quality, and like to eat', and orange tone with a fooling of 'warm and colorful'. In evaluating interrelation between preference and aesthetic value, the study has revealed that ordinary people take the influential factor of 'unity and Gestalt' seriously, while non-professionals preferred 'uniqueness'. Stimulant No. 7 is one of constituent factors of functional table decoration, eliciting significance of images on colors ant aesthetic value. This study also has practical problems about insufficiency or inadequateness in producing mood suitable to T P O, according to depending upon color changes in picking up stimulants, or other problems in selecting stimulants, according to time, seasons and generational parameter in which the inquiry is conducted, but it will serve as a stepping stone for developing new design using both qualitative and quantitative data in 려nctional table decoration.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2004.05b
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• pp.506-510
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• 2004

A torque transmission system composed of several gears and couplings is flexible. In order to get an exact response of motor, the torsional vibration due to an unexpected change of motor speed must be suppressed. Therefore, it is very important that motor control suppress vibration. Various methods to control it including dual inertia system are proposed. Specially, the method of vibration suppression is that vibration can be suppressed to fee㏈ack the estimated torsion torque via the disturbance observer filter being of normal filter. The suitable Proportional controller and coefficient parameter can be designed using CDM and the torsional vibration also be suppressed, but it has a low degree of adaptability to disturbance. The PID controller can be designed easily, but makes the excessive overshoot and oscillation for system response in the early period. To resolve these problems, simple and practical PID controller with two degree of freedom is proposed recently that it ran improve performance of obeying the reference unconcerned in any disturbance by changing the proportional gain by two degree of freedom parameter. But it has also the defect that parameter a must be changed to obtain the ideal Proportional parameter. On this paper, we design the controller which automatically adjusts parameter u using fuzzy Algorithm to overcome such defects. Also, we compare the proposed method with established one and evaluate them to confirm performance of the designed controller.

• Journal of Broadcast Engineering
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• v.28 no.1
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• pp.79-89
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• 2023

A multi-view display is regarded as the most practical technology to provide a three-dimensional effect to a viewer because it can provide an appropriate viewpoint according to the observer's position. But, most multi-view displays with flat shapes have a disadvantage in that a viewer watches 3D images only within a limited front viewing angle. In this paper, we proposed a spherical display using a ball lens with spherical symmetry that provides perfect parallax by extending the viewing zone to 360 degrees. In the proposed system, each projection lens is designed to be packaged into a small modular array, and the module array is arranged in a spherical shape around a ball lens to provide vertical and horizontal parallax. Through the applied optical module, the image is formed in the center of the ball lens, and 3D contents are clearly imaged with the size of about 0.65 times the diameter of the ball lens when the viewer watches them within the viewing window. Therefore, the feasibility of a 360-degree full parallax display that overcomes the spherical aberration of a ball lens and provides a wide field of view is confirmed experimentally.