• 로봇학회논문지
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• 제19권1호
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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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• 제19권spc1호
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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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• 제어로봇시스템학회 1996년도 Proceedings of the Korea Automatic Control Conference, 11th (KACC); Pohang, Korea; 24-26 Oct. 1996
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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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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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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.

• 마이크로전자및패키징학회지
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• 제26권3호
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• pp.43-49
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• 2019

본 연구에서는 그래핀 산화(graphene oxide, GO) 분말 복합 Sn-3.0Ag-0.5Cu(in wt.%) 솔더페이스트를 이용한 플렉시블 기판과 SOP(small outline package) 사이의 솔더 접합부의 굽힘 신뢰성 향상에 관한 새로운 접근을 제안하였다. 솔더페이스트에 GO의 첨가는 녹는점에 약간의 영향을 미치었으나 그 차이는 미미한 것으로 나타났다. 한편, GO의 첨가는 리플로우 공정 동안 솔더 접합부의 금속간화합물(intermetallic compound, IMC) 성장과 두께를 억제 할 수 있음을 확인하였다. 더욱이 접합부의 신뢰성에 미치는 영향을 살펴보고자 반복 굽힘 시험을 진행하였으며 GO 분말의 첨가로 솔더 접합부의 반복 굽힘 신뢰성 향상 시킬 수 있었다. 0.2 wt.%의 GO가 첨가된 솔더 접합부의 경우 GO가 첨가되지 않은 경우에 비하여 굽힘 수명은 20% 가량 증가하는 것으로 나타났다. GO가 첨가된 경우 솔더 접합부의 인장 강도와 연성이 증가하게 나타났는데 이러한 GO 첨가에 의한 기계적 특성 향상이 솔더 접합부의 반복 굽힘 신뢰성 향상에 기여한 것으로 추측된다.

• 대한족부족관절학회지
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• 제17권2호
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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.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1999년도 봄 학술발표회 논문집
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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.

• 한국기계가공학회지
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• 제18권11호
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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.

• 한국인터넷방송통신학회논문지
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• 제18권4호
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• pp.111-116
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• 2018

본 논문에서는 관절 각도계를 사용하여 관절가동범위의 측정하던 것을 각도계를 사용하지 않고 플렉서블 센서를 이용하여 측정하고 측정된 값을 스마트 디바이스와 연동하여 실시간 모니터링이 가능하게 하였다. 현재의 관절가동 범위 측정은 관절 각도기를 활용하여 사람이 직접 측정하고 있다. 이러한 방법은 측정하는 사람의 측정 방법과 위치에 따른 오류로 일관성 있는 측정이 어려워 오차가 발생할 수 있다. 그래서 측정해야 할 관절에 센서를 부착하여 관절의 운동 범위를 측정하였다. 측정을 위한 센서는 플랙서블 형태로 관절의 움직임에 따라 변화되는 저항 값을 측정하는 센서로서 센싱 된 값을 ROM 센서노드를 통하여 무선으로 스마트 디바이스로 전송될 수 있도록 하였다. 개발 된 ROM 측정 장치는 일반적인 관절 각도기를 활용한 측정보다 일관성 있는 측정이 이루어 질 수 있고 스마트 디바이스와 연동하여 실시간 모니터링 함으로써 관절의 움직임에 따른 신속한 진단으로 환자의 빠른 치료와 재활의료 발전에 도움이 될 것이다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1996년도 가을 학술발표회 논문집
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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.