Kyong Kim

Unrelated parallel machine scheduling with setup times using simulated annealing

This paper presents a scheduling problem for unrelated parallel machines with sequence-dependent setup times, using simulated annealing (SA). The problem accounts for allotting work parts of L jobs into M parallel unrelated machines, where a job refers to a lot composed of N items. Some jobs may have different items while every item within each job has an identical processing time with a common due date. Each machine has its own processing times according to the characteristics of the machine as well as job types. Setup times are machine independent but job sequence dependent. SA, a meta-heuristic, is employed in this study to determine a scheduling policy so as to minimize total tardiness. The suggested SA method utilizes six job or item rearranging techniques to generate neighborhood solutions. The experimental analysis shows that the proposed SA method significantly outperforms a neighborhood search method in terms of total tardiness.

Characteristics of the Muscle Activities of the Elderly wearing the Lower limb Orthosis during Gait on the Treadmill

We have developed a lower limb orthosis with a pneumatic rubber actuator, which is intended for the assistance and the enhancement of lower limb muscular activities of the elderly. For this purpose, we investigated the characteristics of the muscular activities with and without the orthosis in gait motion on treadmill. To find out the characteristics of the muscle activities, we analyzed the gait motion of the subject and flexing and extending motion of the knees and measured muscular power in the lower limb. The subjects wearing the lower limb orthosis were instructed to perform gait on the treadmill and flexing and extending motion of the knees in sitting position for monitoring of electromyogram and muscular activities. We used the C8051F Target Board (SILICON LABORATORIES, Inc., USA) for the orthosis control. The air pressure of the pneumatic actuator was varied from one kgf/cm2 to four kgf/cm2 to find the most suitable air pressure. Through this study, we expect to find the effect of the lower limb orthosis in the gait motion and muscular activities along with the most suitable air pressure in the pneumatic actuator of the orthosis for the enhancement of muscular power for the elderly

Development of biosensor using surface acoustic wave

In this research, in using a piezoelectric material of Pb(Mg/sub 1/3/Nb/sub 2/3/)O/sub 3/-PbTiO/sub 3/ (PMN-PT), which has a high electromechanical coupling coefficient, we have tried to see if the material can be practically available as a new surface acoustic wave (SAW) biosensor to detect protein. As the results, the frequency filtering of the central frequency of the PMN-PT substrate is a superior result to that of the LiTaO/sub 3/ (LT) substrate, but the result was not completely satisfactory. We know there is a problem in the design of inter-digital transducer (IDT) pattern. The waves transferred through the input terminal forms SAW which is sure to be transferred to the direction of the output terminal and the backward direction of the input terminal. This reflected wave is reiterated with SAW, which is transferred to the output direction, and so the frequency filtering gives a not good result. The electromechanical coupling coefficient of the PMN-PT substrate is excellent, and as such we can use it as a SAW sensor, in the near future, provided that there is a new IDT design to increase the frequency filtering.

Comparative Analyses of a Rehabilitation Training System for Postural Control Using a Tilting Bed

We propose a rehabilitation training system for postural control using a tilting bed, a visual display and a force plate. Conventional rehabilitation systems for postural control have not been applicable to the patients who have to be lying in bed all the time. The rehabilitation training using those systems is only possible when the patient can stand up by himself or herself. Moreover, there did not exist any device that could provide the sense of balance or the sensation of walking to the patients in bed. The software for the system consists of the training part and the analysis part. The training part has been developed to provide various training scheme that help improve postural control ability of the subjects via repeated training of moving COP. The training consists of the COP maintaining training and the COP movement training in mediolateral, anterior-lateral, and posterior-lateral directions. The analysis part performs the assessments on the COP moving time, COP maintaining time, and mean absolute deviation before and after training for different tilt angles of the bed. Through the experiments ten subjects with the system, we tried to find the effectiveness of the advanced early rehabilitation training system. The results showed that this system is an effective system for early rehabilitation training and that our system can be used as clinical equipment.

Characteristics of the muscle activities of the elderly for various pressures in the pneumatic actuator of lower limb orthosis

There developed a lower limb orthosis with a pneumatic rubber actuator, which can assist and improve the muscular activities in the lower limb of the elderly. For this purpose, the characteristics of the lower limbs muscle activities for various pressures in the pneumatic actuator for the lower limb orthosis was investigated. To find out the characteristics of the muscle activities for various pneumatic pressures, it analyzed the flexing and extending movement of the knees, and measured the lower limbs muscular power. The subjects wearing the lower limbs orthosis were instructed to perform flexing and extending movement of the knees. The variation in the air pressure of the pneumatic actuator was varies from one kgf/cm2 to four kgf/cm2. The muscular power was measured by monitoring electromyogram using MP100 (BIOPAC Systems, Inc.) and detailed three-dimensional motions of the lower limbs were collected by APAS 3D Motion Analysis system. Through this study, it expected to find the most suitable air pressure for the improvement of the muscular power of the aged.

Dynamic characteristics of the SMH actuator using hydrogen- absorbing alloys

The dynamic characteristics of the special metal hydride(SMH) actuator using hydrogen absorbing alloys has been studied through the experiments on the characteristics of the temperature-pressure relation using a Peltier module. The SMH actuator uses the reversible reactions between thermal energy and mechanical energy inside hydrogen-absorbing alloys. It is well known that hydrogen-absorbing alloys can reversely absorb and desorb a large volume of hydrogen gas, more than about 1000 times of their own volume. By using Peltier element, we can actively control the energy conversion through hydrogen-absorbing alloys through hydriding and dehydriding reactions. Heating hydrogen-absorbing alloys using Peltier element will increase the equilibrium pressure of hydrogen gas resulting in the desorption of hydrogen gas by the alloys. Whereas, by cooling the alloys, the equilibrium pressure of hydrogen gas will decrease and hydrogen gas will be absorbed. In the present study, a simple special metal hydride (SMH) actuator, consisting of plated hydrogen-absorbing alloys as a power source, Peltier elements as a heat source, and a cylinder with metal bellows as a mechanical functioning part, has been developed. An electro-less copper plating has been used to improve the thermal conductivity of the hydrogen-absorbing alloys. To study the effects of the electro-less copper plating and the dynamic characteristics of the newly developed SMH actuator, a series of experiments has been performed and analyzed. The experiment demonstrated that the SMH actuator, which contains only 14.5 g of hydrogen-absorbing alloys, was able to easily lift 40 kg of weight with the displacement of 35 mm. The displacement of the cylinder was controlled in the periodic movement. The developed SMH actuator has merits in its small size, light weight, noiseless operation, and compliances similar to those of human bodies. Therefore, the SMH actuator is suitable for uses in medical and rehabilitation applications.