• The Journal of Korea Robotics Society
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• v.19 no.1
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• pp.1-7
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• 2024

This paper presents an under-actuated robotic hand inspired by the ligamentous structure of the human hand for a prosthetic application. The joint mechanisms are based on the concept of a tensegrity structure formed by elastic strings. These rigid bodies and elastic strings in the mechanism emulate the phalanx bones and primary ligaments found in human finger joints. As a result, the proposed hand inherently possesses compliant characteristics, ensuring robust adaptability during grasping and when interacting with physical environments. For the practical implementation of the tensegrity-based joint mechanism, we detail the installation of the strings and the routing of the driving tendon, which are related to extension and flexion, respectively. Additionally, we have designed the palm structure of the proposed hand to facilitate opposition and tripod grips between the fingers and thumb, taking into account the transverse arch of the human palm. In conclusion, we tested a prototype of the proposed hand to evaluate its motion and grasping capabilities.

• Journal of Mechanical Science and Technology
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• v.19 no.spc1
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• pp.357-363
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• 2005

The non-minimum phase characteristic of a flexible manipulator makes tracking control of its tip difficult. The level of the tip tracking performance of a flexible manipulator is significantly affected by the characteristics of the tip reference trajectory as well as the characteristics of the flexible manipulator system. This paper addresses the question of how to best specify a reference trajectory for the tip of a flexible manipulator to follow in order to achieve the objectives of reducing : tip tracking error, residual tip vibration, and the required actuation effort at the manipulator joint. A novel method of tip-based learning controller for the flexible manipulator system is proposed in the paper, where a model of the flexible manipulator system with a command shaping filter is used to generate a smooth and realizable tip reference trajectory for a tip-based learning controller.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10a
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• pp.405-408
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• 1996

Several papers have already been reported on the flexible manipulator with constant arm length. Some of industrial manipulators, however, have sliding joints. It means that the length of their arm or link varies with time. This paper discusses the trajectory contro lof such a manipulator model, and shows some of the experimental results.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.353-353
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• 2000

To control a light weight flexible manipulator, a composite fuzzy controller is proposed. The controller is designed based on two time scaled models. A singular perturbation technique is applied for deriving the models. The proposed controller, however, does not use the complex equilibrium manifold equations, which are usually needed in the controller based on the two time scaled models. The controller for a slow sub-model and a fast sub-model are T-S type fuzzy controllers, which use 3 linguistic variables for each sub-model. A step trajectory is used in simulations as a reference trajectory of joint motions. The results of simulations with the proposed controller show excellent damping of flexible motions compared to a controller with derivative control of flexible motions.

• Journal of the Microelectronics and Packaging Society
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• v.26 no.3
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• pp.43-49
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• 2019

In this study, a new approach using graphene oxide (GO) powder-composited Sn-3.0Ag-0.5Cu(in wt.%) solder paste for improving the bending reliability of solder joints between a flexible substrate and small outline package (SOP) was suggested. The GO addition slightly affected the melting temperature, however, the change in the melting temperature was not significant. Meanwhile, we observed the addition of GO could suppress IMC growth and IMC thickness of solder joint during the reflow process. Moreover, the cyclic bending test was also performed for evaluation of reliability in solder joint and we could improve the cyclic bending reliability of solder joint by adding GO powders. For 0.2 wt.% of GO added to the solder joint, the bending lifetime was increased to 20% greater than that without GO. Pull strength and ductility of the solder joint with GO were also higher than those of the joint without GO and it was assumed that this effect by adding GO could contribute to improve cyclic bending reliability of solder joint.

• Journal of Korean Foot and Ankle Society
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• v.17 no.2
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• pp.115-120
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• 2013

Purpose: Calcaneal lengthening osteotomy is one option for the treatment of symptomatic flexible flatfoot in adults. The aim of the study was to evaluate the short term clinical and radiologic results and analyze its complications. Materials and Methods: Twelve feet who had undergone calcaneal lengthening osteotomy without flexor digitorum longus transfer between December 2009 and July 2011 were included. The mean age was 40.6 years (23~75 years). The mean followup was 17.3 months (13~25 months). Clinical outcome were assessed using American Orthopadics Foot ans Ankle Society (AOFAS) score and visual analogue scale (VAS) for pain. Four radiologic parameters were measured from weightbearing radiographs to evaluate the difference between preoperatively and postoperatively measures. To analyze the complications, calcaneocuboid joint subluxation and degenerative change were measured postoperatively. Results: The mean AOFAS score improved from 55.3 points preoperatively to 82.2 points at lastest follow-up (p=0.000). The mean VAS improved from 6.3 points preoperatively to 3.2 points postoperatively (p=0.002).All radiologic parameters, the mean talonavicular coverage angle on AP view, the mean talo-1st metatarsal angle on AP and lateral view and the mean calcaneal pitch angle, significantly improved after calcaneal lengthening osteotomy. Nine feets (75%) were shown the degenerative change in the calcaneocuboid joint at latest follow-up radiographs. Conclusion: Calcaneal lengthening osteotomy for the symptomatic flexible flatfoot in adults produced significant improvement in clinical and radiologic parameters, but calcaneocuboid joint osteoarthritis occurred postoperatively remained a major problem.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.241-248
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• 1999

The existing bridge with deck joint has many problems during construction and maintenance. To overcome these difficulties, an integral bridge, which is defined as the practice of constructing bridges without deck joints, is proposed in this study. A test bridge with 3 spans of PC beam was selected to verify the function of the bridge and is under construction. Characteristics of integral bridge are followings: $\circled1$ Flexible H-piles under the abutment are installed to accommodate thermal movements of the superstructures of bridge. $\circled2$ PC beam of the superstructure and the abutment are integrated. $\circled3$ The existing approach and relief slabs are applied to minimize the stress transfer occurred from the bridge deck to the pavement. $\circled4$ A cyclic control joint is installed between approach and relief slabs to absorb the thermal movement. $\circled5$ It is used a dual direction bearing which is cheaper than single direction bearing and has a good workability as well. It is also installed a shear block on the top of pier coping to protect the lateral movement caused by temperature change and earthquake.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.11
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• pp.57-62
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• 2019

This paper describes the prediction of eigenfrequencies due to changes in stiffness and mass in the connection area of the lap joint beam in terms of linear and torsional stiffness as well as connection length. The sensitivities of mass and stiffness in the finite element model were derived by using the first-order differential and algebraic equation and were thereafter applied to obtain new natural frequencies that were compared with theoretical exact solutions. Newly predicted natural frequencies due to only a change in stiffness were in relatively good agreement with those in lower modes for rigid joints, while further investigation was needed for flexible joints. On the other hand, only the change in mass resulted in a large discrepancy in the flexible joint case. It may be strongly anticipated that this study will provide a useful tool for estimating modal parameters by change in any design variable, such as the structural dimension, material property, or connection type for a large-scale structure, even though the proposed methodology is currently limited to a jointed beam.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.4
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• pp.111-116
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• 2018

In this thesis, the range of motion of the joint was measured using a flexible sensor without using a goniometer, and the measured values were transferred to a smart device. Current range of joint motion measurement is measured by a person using a goniometer. Since the method of measuring by a person is different according to the measuring method and position of the measuring person, it is difficult to make consistent measurement, and an error may occur. The sensor for measurement is a flexible sensor that measures the resistance value that changes according to the movement of the joint. The sensed value can be transmitted to the smart device wirelessly through the ROM sensor node. Also, the sensed analog values were converted to digital values using an ADC. The converted value can be transmitted to the smart device wirelessly through the sensor node. The developed ROM measuring device can perform more consistent measurement than the measurement using general articulator and real time monitoring by interlocking with smart device, so that rapid diagnosis according to the movement of the joint can help the patient's rapid treatment and rehabilitation medical advancement will be.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1996.10a
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• pp.121-128
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• 1996

In this study design and construction technique for joint-less integral abutment for short to mid span bridges was developed. Expansion of superstructure due to thermal effect was absorbed in the flexible pile-type abutment in stead of expansion joint in the conventional bridges. Design method for pile subject to vertical and horizontal force was proposed. Backfill, approach slab and details of its connection joint with pavement was also proposed.