• Journal of the Korean Institute of Intelligent Systems
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• v.21 no.1
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• pp.80-85
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• 2011

This paper presents the design of the power-assisted controller for the in-wheel type smart wheelchair by using torque estimation that is predicted by relationship between input voltage and output wheel angular velocity. Nowadays, interest of the moving assistant aids is increased according to the increase in population of the elderly and the handicapped person. However some of the moving assistant aids have problems. For example, manual wheelchair has difficulty moving at the slope, because users lack the muscular strength of their arm. In electric wheelchair case, users should be weak by being decreased muscles of upper body. To overcome these problems, power-assisted electric wheelchair are proposed. Most of the power-assisted electric wheelchair have the special rims that can measure the user's power. In here, the rims have to be designed to install the sensors to measure user's power. In this paper, we don't design the rim to measure the man power. To predict the man power, we propose a control algorithm of the in-wheeled electric wheelchair by using torque estimation from the wheel. First, we measure the wheel velocity and voltage at the in-wheel electric wheelchair. And then we extract driving will forces by using proposed mathematical model. Also they are applied at the controller as the control input, we verify to be able to control in-wheel type smart wheelchair by using simulation.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.10
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• pp.928-935
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• 2015

This paper presents low temperature structural tests of a UAV wing which has room temperature-curing adhesive bond. The wing structure is made of carbon fiber reinforced composites, and the skins are bonded to the inner structures (such as ribs and spars) using room temperature-curing adhesive bond. Also, to verify damage tolerance design of the wing structure, barely visible impact damages are intentionally created in the critical areas. The attachment fittings of the wing are fixed in a specially designed chamber which can simulate the low temperature environments of the operating altitudes. The test load is applied by hydraulic actuators which are placed outside the chamber. The structural tests consist of strain survey tests and a durability test for 1-life fatigue load spectrum. During the tests, strains of major parts are measured by strain gauges and FBG sensors. The change of the initial impact damages is also monitored using piezoelectric sensors. The 1-life damage tolerance of the composite structure is verified by the structural tests under the simulated environments.

• The Transactions of the Korean Institute of Power Electronics
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• v.13 no.3
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• pp.171-178
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• 2008

Pressure control of hydraulic pump using SRM with pressure predictor and direct torque control method is presented in this paper. Nowadays, high efficiency and high performance motor drive is much interested in hydraulic pump system. But the hydraulic pump system has an inherent defect that its dynamic behavior causes by interaction between the sensor and hydraulic load. It will make low performance of whole system, even unstable and oscillatory. Proposed system integrates pressure predictor and direct instantaneous torque control (DITC). The pressure predictor includes Smith predictor, which is easy to improve unstable or long oscillation in traditional negative feedback control and popular PID control architectures. And DITC method can reduce inherent torque ripple of SRM, and develop smooth torque to load, which can increase stability and improve the torque response of SR drive. So high dynamic performance and stabilization can achieved proposed hydraulic system. At last, the proposed hydraulic system is verified by simulation and experimental results.

• Journal of Sensor Science and Technology
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• v.22 no.2
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• pp.150-155
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• 2013

Recently, various hearing aids are developed to overcome hearing loss. There are available hearing aids, such as air conduction hearing aid, implantable middle ear hearing aid and so on. But air conduction hearing aid is inconvenience caused by howling, and ossicle chain driving type implantable middle ear hearing aid has some week point due to problem of possible nercobiosis of coupling spot along incus long process. In recent years, in order to improve these shortcomings round window (RW) driving hearing aid has been paying attention. In this paper, the physical cochlear model is proposed for a performance evaluation of the RW driving hearing aids of a transducer. In order to verify an experiment proposed on a performance of physical cochlear model, the transducer which has ossicles characteristics is used. By measuring and comparing the frequency characteristics of transducer with ossicles and human temporal bone, performance of physical cochlear model was verified. As from the result of experiment, it is expected that an implemented cochlear model is useful for evaluating characteristics of RW transducer.

• Journal of Convergence for Information Technology
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• v.7 no.5
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• pp.95-102
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• 2017

Modular toys for creative education require functional blocks to create various types of movements. An active drive module and a lot of passive connection blocks are needed to express motion with combination. In this paper, we propose the design of modular toys to produce various creative movements and controller structure working with them. In order to facilitate the connection between the designed modules, a connection method and a suitable mechanism are suggested. We also dealt with the design of various types of sensor modules that can work in conjunction with modular toys. Using these toys, typical standard application form that can be imitated educationally is suggested and showed the usefulness of the modular toy by actually applying it with designed modules and components. The proposed method is applied to actual educational toys, and the operation is effectively performed by recording operation and playing repetitive operation.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.11
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• pp.48-55
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• 2016

Ambient-light sensor system, which changes the brightness of a display as ambient light change, was studied to reduce the power consumption of the mobile applications such as note PC, tablet PC and smart phone. The ambient-light sensor system should be integrated on a display panel to improve the complexity and cost of mobile applications, so the ambient-light sensor and readout circuit was integrated on a display panel using low-temperature poly-silicon thin film transistors (LTPS-TFT). We proposed the new compensation method to correct the panel-to-panel variation of the ambient-light sensors, without additional equipment. We designed and investigated the new readout circuit with the proposed compensation method and the analog-to-digital converter for the final digital output of ambient light. The readout circuit has very simple structure and control timing to be integrated with LTPS-TFT, and the input luminance ranges from 10 to 10,000 lux. The readout rate is 100 Hz, and maximum differential non-uniformity with 20 levels of the final output below 0.5 LSB.

• Journal of Sensor Science and Technology
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• v.8 no.6
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• pp.427-433
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• 1999

In this paper, we have presented an one-axis fluxgate magnetic sensor with ferrite core, excitation, and pick-up coil. This magnetometer is consist of a sensing element, driving circuits for excitation coil and signal processing for detecting second harmonic frequency component which is proportional to the DC magnetic to be measured. The sensor core is excited by a square waveform of voltage through 82 turns of the excitation coil. The second harmonic output of pick-up coil(150 turns) is measured by a FFT spectrum analyzer. This result is compared to output of PSD(phase sensitive detector) unit for detecting a second harmonic component. The measured sensitivity is about 50 V/T at driving frequency of 2 kHz. The nonlinearity of fluxgate magnetic sensor is calculated about 2.0%.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.5
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• pp.605-609
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• 2010

In modern surveillance equipment, infrared (IR) sensors are essential for detection and observation. The IR sensor is connected to a miniature cryogenic cooler to maintain the temperature at very low levels, i.e., temperatures as low as 77 K. However, the quality of the image captured by the sensor is degraded by the transmission of vibration disturbances from the cooler. Therefore, to maintain high image quality, the compressor vibration and the force transmitted to the sensor have to be mitigated. For the compressor vibration isolating system, a tuned dynamic vibration absorber, combined with a passive isolator, is proposed. A cryogenic compressor bracket and springs are designed to allow the absorber mass to mitigate the vibration jitter in the axial direction. The system design is analyzed and evaluated in terms of the dynamic suppression of the harmonic force at the operating frequency of the cooler.

• Journal of the Korea Convergence Society
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• v.11 no.11
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• pp.195-201
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• 2020

This paper implemented quadcopter-type drone system and proposed the heuristic method for obtaining the optimum gain coefficients in order to minimize the settling time. Control system for quadcopter posture stabilization reads the posture data from accelerator and gyro sensor, revises the original posture data using Mahony filter, and drives 4 DC motors using PID controller. The first step of the proposed method is to obtain the gain coefficients using the Ziegler-Nichols method, and then determine the optimum gain coefficients using the heuristic method at the next 3 steps. The experimental result shows that the maximum overshoot decreases from 44.3 to 29.8 degrees and the settling time decreases from 2.6 to 1.7 seconds compared to the Ziegler-Nichols method. Therefore, we proved that the proposed method works well in quadcopter flight system with high motor noise while reducing trial and error to obtain the optimal PID gain coefficients.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.1
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• pp.9-18
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• 2013

In this paper, we have developed the intellectual kegel trainer with the biofeedback. The pelvic muscles of female are composed of a slow twitch fiber and a fast twitch fiber. If two twitch fiber be not well done, then the urine be frequently called by nature. In order to recover the function of pelvic muscles, we use the kegel trainer with biofeedback training. Such a trainer make strengthen the weakness pelvic muscles by biofeedback training and get exercise the pelvic muscles in physical suppress of 10 kg. The biofeedback training against the physical suppress can have strengthen the pelvic muscles and can display the operation graph of strengthen movement in monitor.