• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.11a
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• pp.167-168
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• 2012

Analysis on structural effects which are reduction of friction coefficient and increase of tendon area by HDPE greased and large size strand in post-tensioning system of reactor containment building was carried out. Effective ratio of tendon force increases 67% to 83% by HDPE greased strand and vertical, horizontal internal section forces increased maximum 51%, 41% respectively. Tendon quantity could be reduced 30% by large size and HDPE greased strand that can maintain safety of ultimate internal pressure same as at present.

• The Journal of Korea Robotics Society
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• v.9 no.4
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• pp.258-263
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• 2014

An adaptive robot hand (AR-Hand) has a stable grasp of different objects in unstructured environments. In this study, we propose an AR-Hand based on a tendon-driven mechanism which consists of 4 fingers and 12 DOFs. It weighs 0.5 kg and can grasp an object up to 1 kg. This hand based on the adaptive grasp mechanism is able to provide a stable grasp without a complex control algorithm or sensor system. The fingers are driven by simple tendon structures with each finger capable of adaptively grasping the objects. This paper presents a method to decide the joint stiffness. The adaptive grasping is verified by various grasping experiments involving objects with different shapes and sizes.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.663-667
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• 2000

The equivalent load method has been widely used in the design and analysis of prestressed concrete structures. The purpose of this paper is to explore several important method of obtaining equivalent loads and to clarify the advantages and limitations of each method. The methods devised in this study include the use of curvature of tendon, characteristics of primary moment, self-equilibrium conditions, and linear segments approximation of tendon. It is shown that equivalent lading system is not uniquely determined in some cases and careful engineering judgement is required from the view point of accuracy and practical convenience.

• Journal of the Korea Concrete Institute
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• v.13 no.1
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• pp.1-8
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• 2001

Recently, prestressed concrete(PSC) bridge structures with many repetitive spans have been widely constructed using the segmental construction method in many countries. In these segmentally constructed PSC bridges, there exist many construction joints which is required coupling of tendons or overlapping of tendons to introduce continuous prestress through several spans of bridges. The purpose of this paper is to investigate in detail the complicated stress distributions around the tendon coupled joints in prestressed concrete girders. To this end, a comprehensive experimental program has been set up and a series of specimens have been tested to identify the effects of tendon coupling. The present study indicates that the longitudinal and transverse stress distributions of PSC girders with tendon couplers are quite different from those of PSC girders without tendon couplers. It is seen that the longitudinal compressive stresses introduced by prestressing are greatly reduced around coupled joints according to tendon coupling ratios. The large reduction of compressive stresses around the coupled joints may cause deleterious cracking problems in PSC girder bridges due to tensile stresses arising from live loads, shrinkage and temperature effects. The analysis results by finite element method correlate very well with test results observed complex strain distributions of tendon coupled members. It is expected that the results of this paper will provide a good basis for realistic design guideline around tendon coupled joints in PSC girder bridges.

• Computers and Concrete
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• v.13 no.4
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• pp.501-516
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• 2014

The purpose of this study was to investigate the performance of precast concrete pier cap system. The proposed precast pier cap provides an alternative to current cast-in-place systems, particularly for projects in which a reduced construction time is desired. Five large-scale pier cap specimens were constructed and tested under quasistatic monotonic loading. The computer program, RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology) was used for the analysis of reinforced concrete structures. A bonded tendon element is used based on the finite element method, and can represent the interaction between the tendon and concrete of a prestressed concrete member. A joint element is used in order to predict the inelastic behaviors of segmental joints with a shear key. This study documents the testing of the precast concrete pier cap system under monotonic loading and presents conclusions and design recommendations based on the experimental and analytical findings. Additional full-scale experimental research is needed to refine and confirm design details, especially for actual detailing employed in the field.

• Structural Engineering and Mechanics
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• v.69 no.3
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• pp.307-315
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• 2019

This paper proposes a chattering-free sliding mode control (CFSMC) method for seismically excited structures. The method is based on a fuzzy logic (FL) model applied to smooth the control force and eliminate chattering, where the switching part of the control law is replaced by an FL output. The CFSMC is robust and keeps the advantages of the conventional sliding mode control (SMC), whilst removing the chattering and avoiding the time-consuming process of generating fuzzy rule basis. The proposed method is tested on an 8-story shear frame equipped with an active tendon system. Results indicate that the new method not only can effectively enhance the seismic performance of the structural system compared to the SMC, but also ensure system stability and high accuracy with less computational cost. The CFSMC also requires less amount of energy from the active tendon system to produce the desired structural dynamic response.

• Journal of the Earthquake Engineering Society of Korea
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• v.13 no.2
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• pp.15-27
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• 2009

The purpose of this study is to investigate the seismic behavior of precast segmental PSC bridge columns. For the analysis of reinforced concrete structures, a computer program named RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology) is used. To represent the interaction between tendon and concrete of a prestressed concrete member, a bonded or unbonded tendon element based on the finite element method is used. A joint element is modified to predict the inelastic behaviors of segmental joints. The solution of the equations of motion is obtained by numerical integration using Hilber-Hughes-Taylor (HHT) algorithm. The proposed numerical method gives a realistic prediction of seismic behavior throughout the input ground motions for numerical examples.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.10
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• pp.1039-1046
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• 2009

In this work, a bilateral control for a master-slave manipulator system which will be used for handling objects contaminated by radioactivity has been addressed. The links of manipulators are driven independently by individual motors installed on the base and the driving torque is transmitted through pre-tensioned tendons. The measurable variables are the positions and rates of master/slave motors. In the consideration of the flexibility of the tendon and available measurements for control, we proposed an optimal static output feedback control for possible bilateral control architecture. By using modal analysis, the system model is reduced to guarantee the detectability which is a necessity for the static output feedback control design. Based on the reduced model, the control gains are determined to attenuate vibration in the sense of optimality. The feasibility of the proposed control design was verified along with some simulation results.

• The Journal of Churna Manual Medicine for Spine and Nerves
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• v.1 no.2
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• pp.81-92
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• 2006

Objectives: To review recent findings from physiologic research about the nature of proprioceptive spinal reflex, proposed explanation for mechanisms of musculoskeletal problems associated with propriceptive dysfunction and techniques controlling this problem. Methods: MEDLINE databases were searched using various combinatins of the keywords proprioception, spinal reflex, somata-somatic reflex, spinal manipulation, muscle spindle, Golgi-tendon organ, along with searching the related articles and textbooks. Results and Conclusion: Proprioceptors(muscle spindle, Golgi-tendon organs) monitor the position of joints, tension in tendons and ligaments, and the state of muscular contraction. Disturbed activity of proprioceptive spinal reflex can cause chronic state of increased muscle stiffness, pain, deficiencies both in muscle coordination and propioception, and so on. All kinds of techniques that control proprioceptive primary afferent neurons can affect the motor control system and evoke changes in the neuromuscular system.

• Clinics in Shoulder and Elbow
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• v.26 no.4
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• pp.366-372
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• 2023

Background: There is minimal literature on the morphology of partial distal biceps tendon (DBT) tears. We sought to investigate tear morphology by retrospectively reviewing 3-Tesla magnetic resonance imaging (3T MRI) scans of elbows with partial DBT tears and to propose a basic classification system. Methods: 3T MRI scans of elbows with partial DBT tears were retrospectively reviewed by two experienced observers. Basic demographic data were collected. Tear morphology was recorded including type, presence of retraction (>5 mm), and presence of discrete long-head and short-head tendons at the DBT insertion. Results: For analysis, 44 3T MRI scans of 44 elbows with partial DBT tears were included. There were 9 isolated long-head tears (20%), 13 isolated short-head tears (30%), 2 complete long-head tears with a partial short-head tear (5%), 5 complete short-head tears with a partial long-head tear (11%), and 15 peel-off tears (34%). Retraction was seen in 5 or 44 partial tears (11%), and 13 of the 44 DBTs were bifid tendons at the insertion (30%). Conclusions: Partial DBT tears can be classified into five sub-types: long-head isolated tears, short-head isolated tears, complete long-head tears with partial short-head involvement, complete short-head tears with partial long-head involvement, and peel-off tears. Classification of tears may have implications for operative and non-operative management. Level of evidence: III.