• Journal of the Ergonomics Society of Korea
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• v.31 no.6
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• pp.757-764
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• 2012

Objective: The aim of this study is to find the optimal values of sliding factors which influence the mechanical emotion of users when they use sliding type mobile phones. Background: There are various researches that study the emotion of using mobile phones. They focus the correlation between emotion words and design factors and use the commercial products by the subjects in the experiment. However, it has a limit in finding the optimal point of emotional factors because we can search the restricted values in the mass production of the products. Therefore, we will find the optimal points by realizing the full range of the user's mechanical emotion. Method: First, we need to get the detailed factors which can describe the mechanical emotion in sliding up and down the mobile phone. Next, we find the control factors by considering the correlation between the factors of the sliding emotion and the possibility of quantitative design. To find the optimal points on the control factors, we make a sliding evaluation system which can help users feel the sliding mechanical emotion by realizing control factors. Finally, we find the optimal points by doing the experiment the system being used. Results: The critical values of the factors which are the main variables of this study are Open Max Force and Dead point Ratio. The optimal point of the Open Max Force is 200~250g/f, and the Dead point Ratio is 40~50%. Conclusion: In this study we develop the sliding evaluation system to realize the control factors of the sliding type phone and find the optimal values of the critical factors. Application: The results can be used as the criteria for designing sliding type phone.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.609-612
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• 2007

The HDD (hard disk drive) using Load/Unload (L/UL) technology includes the benefits which are increased areal density, reduced power consumption and improved shock resistance than those of contact-start-stop (CSS). Dynamic L/UL has been widely used in portable hard disk drive and will become the key technology for developing the small form factor hard disk drive. The main design objectives of the L/UL mechanisms are no slider-disk contact or no media damage even with contact during L/UL, and a smooth and short unloading process. In this paper, we focus on lift-off force, pitch static attitude (PSA), roll static attitude (RSA) and dimple point. The "lift-off" force, defined as the minimum air bearing force, is another very important indicator of unloading performance. A large amplitude of lift-off force increases the ramp force, the unloading time, the slider oscillation and contact-possibility. PSA and RSA are also very important parameters in L/UL system and stability of slider is mainly determined by PSA and RSA. Dimple point by PSA and RSA is also important indicator. Therefore we find the optimal dimple point of SFF HDD suspension for improving the unloading performance.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.3 s.96
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• pp.272-279
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• 2005

In this study the optimal isolation system for the prototype HIFD(high impulsive force device) is investigated. For this purpose, firstly, the dynamic behavior of a human body and a transmitted force under specific operation conditions are analyzed through a series of experimental works using the devised test setup. In order to design the optimal dynamic absorbing system, the parameter optimization process is performed using the simplified isolation system model based on the experimental results of linear impulse and transmitted force. Finally, under the parameters satisfying the constraints of the buffering displacement and the transmitted force, the performance of the designed isolation system for the prototype HIFD is evaluated by experiment.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.644-647
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• 1997

Asymmetric cylinders are usually used as an actuator of active suspensions. The conventional optimal controller design does not include actuator dynamics as a state and force controller is needed to track the desired force. But the actuator is not ideal, so performance of an active suspension system is degraded. In this paper, we take account nonlinear actuator dynamics and obtain a linear model using a feedback linearization technique then apply optimal control method. Effectiveness of proposed method is demonstrated by numerical simulation of 1/4 car model.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.1
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• pp.40-45
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• 2008

This paper presents an optimal design of a permanent magnet actuator(PMA) using a parallel genetic algorithm. Dynamic characteristics of permanent magnet actuator model are analyzed by coupled electromagnetic-mechanical finite element method. Dynamic characteristics of PMA such as holding force, operating time, and peak current are obtained by no load test and compared with the analyzed results by coupled finite element method. The permanent magnet actuator model is optimized using a parallel genetic algorithm. Some design parameters of vertical length of permanent magnet, horizontal length of plunger, and depth of permanent magnet actuator are predefined for an optimal design of permanent magnet actuator model. Furthermore dynamic characteristics of the optimized permanent magnet actuator model are analyzed by coupled finite element method. A displacement of plunger, flowing current of the coil, force of plunger, and velocity of plunger of the optimized permanent magnet actuator model are compared with the results of a primary permanent magnet actuator model.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.12
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• pp.64-69
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• 2002

In this study, the optimal dynamic isolation system for gas operated combat weapon has been investigated. For this purpose, firstly, the dynamic behavior of human induced by firing operations has been analyzed through a series of experimental works using the devised test setup. The characteristics of linear impulse has been compared under some conditions of support system. In order to design the optimal dynamic isolation system, parameter optimization process has been performed based on the simplified isolation system under constraints of moving displacement and transmitted force. Finally, the performance of the designed dynamic absorbing system has been evaluated by simulation.

• Journal of the Ergonomics Society of Korea
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• v.32 no.6
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• pp.511-516
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• 2013

Objective: The objective of this study is designing an optimal hand tool through maximum grip force study accordance to the hand grip span. Background: In order to prevent musculoskeletal diseases, studies on hand tool design are proceeding based on grip strength, finger force, and contribution of individual finger force on total grip strength. However, experimental apparatus using a tool that is actually used in work place was almost non-existent. Method: 19 males were participated in an experiment. Using the load cell inserted real plier, finger force, grip strength, and subjective discomfort rate of both hands (dominant and non-dominant) were measured in 5 different hand grip span(45mm, 50mm, 60mm, 70mm, and 80mm). Results: There was significant difference(p<0.001) of total grip strength, individual finger force and subjective discomfort rating according to various hand grip span(45, 50, 60, 70, and 80mm). Also, statistically significant different(p<0.001) was shown between the dominant hand and non-dominant hand. In addition, individual finger force in maximum grip was in order of middle finger, ring finger, index finger, and little finger. Conclusion: Optimal grip span of pliers that exerting maximum grip strength is 50~60mm. Application: This finding is expected to be used for designing proper pliers.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.792-800
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• 2021

This paper presents a new structure for a linear active magnetic bearing using a Halbach magnet array. The proposed magnetic bearing consisted of a Halbach magnet array, center magnet, and single coil. The proposed linear active magnetic bearing has a high dynamic force compared to the previous study. The high dynamic force could be obtained by varying the thickness of a horizontally magnetized magnet. The new structure of Halbach linear active magnetic bearing has a high dynamic force. Therefore, the proposed linear active magnetic bearing increased the bandwidth of the system. Magnetic modeling and optimal design of the new structure of the Halbach linear active magnetic bearing were performed. The optimal design was executed on the geometric parameters of the proposed linear active magnetic bearing using Sequential Quadratic Programming. The proposed linear active magnetic bearing had a static force of 45.06 N and a Lorentz force constant of 19.54 N/A, which is higher than previous research.

• 제어로봇시스템학회:학술대회논문집
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• 1986.10a
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• pp.113-118
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• 1986

The feedback controllers for the active vibration control of elastic systems are developed using optimal regulator, optimal tracking, time optimal and noise observer algorithms. Using the modal analysis of the elastic systems, the effects of the actuator positions, the input weighting factor and the magnitude of the constraint of the actuator force are investigated.

• The Journal of Korea Robotics Society
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• v.6 no.2
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• pp.130-140
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• 2011

This paper proposes an optimal posture for the task-oriented movement of dual arm manipulator. A stability criterion function which consists of three kinds of feature-representative parameters has been utilized to define the optimal posture. The first parameter is the force which is applied to the object. The torque of each joint and position of arm are attained from the current sensor and encoder, respectively. From these two data, the applied force to an object is estimated using sum of vectors of the joint torques estimated from the measured current. In order to investigate the robustness of each posture, the variation of the end-effector from the encoder information has been utilized as the second parameter. And for the last parameter for the optimality, the total energy consumption has been used. The total consuming energy of each posture can be computed from the current information and the battery voltage. The proposed robot structure consists of a mobile inverted pendulum and dual manipulators. In order to define the optimal posture for the each object, external disturbances are applied to the mobile inverted pendulum robot and the first and second parameters are investigated to find the optimal posture among the pre-selected most representative postures. Finally, the proposed optimal posture has been verified by the proposed stability criterion function which consists of total force to the object, the fluctuation of the end-effector position, and total energy consumption. The effectiveness of the proposed algorithms has been verified and demonstrated through the practical simulations and real experiments.