• BMB Reports
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• v.51 no.12
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• pp.623-629
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• 2018

For mechanical force to induce changes in cellular behaviors, two main processes are inevitable; perception of the force and response to it. Perception of mechanical force by cells, or mechanosensing, requires mechanical force-induced conformational changes in mechanosensors. For this, at least one end of the mechanosensors should be anchored to relatively fixed structures, such as extracellular matrices or the cytoskeletons, while the other end should be pulled along the direction of the mechanical force. Alternatively, mechanosensors may be positioned in lipid bilayers, so that conformational changes in the embedded sensors can be induced by mechanical force-driven tension in the lipid bilayer. Responses to mechanical force by cells, or mechanotransduction, require translation of such mechanical force-induced conformational changes into biochemical signaling. For this, protein-protein interactions or enzymatic activities of mechanosensors should be modulated in response to force-induced structural changes. In the last decade, several molecules that met the required criteria of mechanosensors have been identified and proven to directly sense mechanical force. The present review introduces examples of such mechanosensors and summarizes their mechanisms of action.

• The korean journal of orthodontics
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• v.24 no.2
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• pp.295-301
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• 1994

The movement of teeth during orthodontic treatment requires bone remodeling process in periodontal tissue. To find out the changes occuring in the cell itself, mechanical force was applied to the cultured periodontal ligament cells. Following results were obtained from measuring the changes in cyclic AMP and $PGE_2$, $^3H$-thymidine incorporation amount in time lapse after application of mechanical force. 1. When mechanical force was applied to cultured PDL cells, the amount of cAMP in cells were increased significantly after 15 min. of force application, but were decreased gradually as time lapsed. 2. When mechanical force was applied to cultured PDL cells, the amount of PGE2 were increased at 20,40,60 min. and was significantly increased at 20 min. 3. When mechanical force was applied to cultured PDL cells, the amount of $^3H$-thymidine incorporation was some increased, but was not statistically significant.

• Journal of Mechanical Science and Technology
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• v.20 no.5
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• pp.668-674
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• 2006

In order to develop a cell based robot, we present a micro-mechanical force measurement system for the biological muscle actuators, which utilize glucose as a power source. The proposed measurement system is composed of a micro-manipulator, a force transducer with a glass probe, a signal processor, an inverted microscope and video recording system. Using this measurement system, the contractile force and frequency of the cardiac myocytes were measured in real time and the magnitudes of the contractile force of each cardiac myocyte under different conditions were compared. From the quantitative experimental results, we could estimate that the force of cardiac myocytes is about $20\sim40{\mu}N$, and show that there are differences between the control cells and the micro-patterned cells.

• Journal of Sensor Science and Technology
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• v.15 no.4
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• pp.251-256
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• 2006

This paper describes the flexible force sensor using fiber Bragg grating (FBG) and silicone rubber for the tactile sensation to detect the distributed normal force. The newly designed FBG flexible force has simple structure and can be easily multiplexed with simple wiring compared with the other electric mechanical sensors. We designed the flexible silicone rubber transducer and found the optimum embedding position of FBG in the transducer using the finite element analysis. This flexible force sensor has good performance and is immunity to the electromagnetic field compared with any other kinds of small force sensors for tactile sensation.

• Journal of Mechanical Science and Technology
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• v.19 no.spc1
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• pp.422-428
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• 2005

In this paper, the contact force between two colliding bodies is modeled by using Hertz's force-displacement law and nonlinear damping function. In order to verify the appropriateness of the proposed contact force model, the drop type impact test is carried out for different impact velocities and different materials of the impacting body, such as rubber, plastic and steel. In the drop type impact experiment, six photo interrupters in series close to the collision location are installed to measure the velocity before impact more accurately. The characteristics of contact force model are investigated through experiments. The parameters of the contact force model are estimated using the optimization technique. Finally the estimated parameters are used to predict the impact force between two colliding bodies in opening action of the magnetic contactor, a kind of switch mechanism for switching electric circuits.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1651-1656
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• 2005

This paper describes a natural frequency analysis conducted to find out a suitable working area for a spring-manipulator system generating a large vibrating force with mechanical resonance. Large force generation is one of the functions that we hope for a robot. For example, a weeding robot is required to generate a large force, because some weeds have roots spreading deeply and tightly. The spring-manipulator system has a spring element as an end-effector, so it can be in a state of resonance with the elasticity of the spring element and the inertial characteristics of the manipulator. A force generation method utilizing the mechanical resonance has potential to produce a large force that cannot be realized by a static method. A method for calculating a natural frequency of a spring-manipulator system with the generalized inertia tensor is proposed. Then the suitable working area for the spring-manipulator system is identified based on a natural frequency analysis. If a spring-manipulator system operates in the suitable working area, it can sustain mechanical resonance and generate a large vibrating force. Moreover, it is shown that adding a mass at the tip of the manipulator expands the suitable working area.

• The Journal of Korea Robotics Society
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• v.10 no.4
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• pp.179-185
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• 2015

The versatility of a human hand is what the researchers eager to mimic. As one of the attempt, the redundant degree of freedom in the human hand is considered. However, in the force domain the redundant joint causes a control issue. To solve this problem, the force control method for a redundant robotic hand which is similar to the human is proposed. First, the redundancy of the human hand is analyzed. Then, to resolve the redundancy in force domain, the artificial minimum energy point is specified and the restoring force is used to control the configuration of the finger other than the force in a null space. Finally, the method is verified experimentally with a commercial robot hand, called Allegro Hand with a force/torque sensor.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.3
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• pp.1-6
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• 2008

The performance of shock absorber is directly related to the car behavior and performance, both for handling and comfort. Most of compact car are assembled the passive shock absorber for cost effect but some of compact driver want better performance of shock absorber than standard parts. Therefore, they want the semi-active suspension control system instead of standard damper system. But they only can change the mechanical damping control shock absorber at A/S market. The mechanical damping control shack absorber can not vary the damping force in driving condition so they do not satisfy the mechanical damping control shock absorber system. In this study, electrically damping force controlled shock absorber system is developed based on the mechanical damping force control damper system. This system can vary damping force by switch on dashboard in driving condition. And, this system can satisfy the requirement of tuning market. Therefore, it is expected the system to show the engineering capability of korean damper company and to increase export market share to oversea damper market.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.28 no.4
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• pp.158-164
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• 2016

Currently, identifying a new carbon-free energy resource is important in order to resolve the global warming problem. Along the same line, this paper studied how to convert magnetic force into mechanical force and a new basic mechanism of converting magnetic force into mechanical force was identified. Long-term reliability test, around 15 million times, was also conducted at $-1^{\circ}C{\sim}27^{\circ}C$ to evaluate the durability of magnetic force. As a result, tests showed that the deviation of the mechanical force was within 0.8% of the initial force, and the relation between repulsive force (P) and ambient temperature (T) was formulated in a linear equation P = -0.175T+78.945.

• Journal of Mechanical Science and Technology
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• v.16 no.7
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• pp.873-881
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• 2002

In this paper, a on-line estimation method of the radial immersion angle using cutting force is presented. The ratio of cutting forces in feed and cross-feed directions acting on the single tooth at the immersion angle is a function of the immersion angle and the ratio of radial to tangential cutting force. It is found that the ratio of radial to tangential cutting force is not affected by cutting conditions and axial rake angle, which implies that the ratio determined by one preliminary experiment can be used regardless of the cutting conditions for a given tool and workpiece material. Using the measured cutting force during machining and predetermined ratio, the radial immersion ratio is estimated in process. Various experimental results show that the proposed method works within 5% error range.