• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.6
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• pp.545-550
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• 2013

We present a tactile information transceiver using a friction-tunable slider-pad. While previous tactile information devices were focused on either input or output functions, the present device offers lateral position/vertical direction detection and texture expression. In characterizing the tactile input performance, we measured the capacitance change due to the displacement of the slider-pad. The measured difference for a z-axis click was 0.146 nF/$40{\mu}m$ when the x-y axis navigation showed 0.09 nF/$750{\mu}m$ difference. In characterizing the texture expression, we measured the lateral force due to a normal load. We applied a voltage between parallel electrodes to induce electrostatic attraction in DC and AC voltages. We measured the friction under identical fingertip action conditions, and obtained friction in the range of 32-152 mN and lateral vibration in the force range of 128.1 mN at 60 V, 2 Hz. The proposed device can be applied to integrated tactile interface devices for mobile appliances.

• Journal of the Korea Convergence Society
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• v.9 no.2
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• pp.303-311
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• 2018

Squat exercise is one of the free weight exercises that are recognized as important from a bio-mechanical point of view. It is an important exercise to train lower extremity muscles in daily activities or sports activities and to strengthen trunk and lower body strength. It is effective and accurate to use a variety of assistive devices to calibrate athletic posture with squat exercise supported interactive device. The issues of the structural analysis for design a foot plate for squat exercise is to model the behavior by simplifying the dynamic behavior. In this paper, the authors proposed a exercise system design method for the vertical load distribution and bio-mechanical signal process used for the squat exercise mechanism analysis, and based on these results, designed device can make the more safe and reliable free weight exercise. It is applied to system design through design method with kinematic dynamic, VR device and estimation model of exercise.

• The KSFM Journal of Fluid Machinery
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• v.19 no.4
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• pp.48-53
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• 2016

The centrifugal separator which uses gravity separation method for oil-water separation, rotating at high-speed, is one of the most commonly used device for controlling the amount of the oil in waste water collected in bilge. The IMO (International Maritime Organization) has set regulations, also known as MARPOL 73/78, for the prevention of marine pollution. In addition, DET NORSKE VERITAS (DNV) has set standards regarding the assignment of Environmental Class Notation, CLEAN or CLEAN DESIGN, of ships. One of the requirements for classification is that in addition to conforming to MARPOL 73/78, more stringent measures must be taken as well. One of these measures is to limit the oil concentration in bilge water to less than 5ppm. So in this study, an Oil-Water Separator (OWS) is used together with multiple separating plates as a filtration system to be used as an oil-water separation device. The OWS operates using centrifugal separation in which the mixture is separated by centrifugal forces. The main purpose of this paper is to present the OWS separation efficiency according to the rotation speed, mass-flow rate, the angle and the number of stacked layers of the laminated plate using Computational Fluid Dynamics (CFD). Improvements to the device will be investigated from these results.

• Journal of Aerospace System Engineering
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• v.12 no.2
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• pp.37-45
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• 2018

A two-axis gimbal-type antenna for a Compact Advanced Satellite (CAS) is used to efficiently transmit high resolution image data to a ground station. In this study, we designed the structure of a two-axis gimbal-type antenna while applying a launch lock device to secure its structural safety under a launch environment. To validate the effectiveness of the structural design, a structural analysis of the antenna was performed. First, a modal analysis was performed to investigate the dynamic responses of the antenna with and without the mechanical constraints of the launch lock device. In addition, a quasi-static analysis was performed to confirm the structural safety of the antenna structure and bolt I/Fs between the antenna base and the satellite. The suitable range of constraint force on the launch lock device was also determined to ensure the structural safety and mechanical gapping of the ball & socket interfaces, which places multi-constraints on the azimuth and elevation stage of the antenna.

• Journal of the Korean Institute of Intelligent Systems
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• v.25 no.6
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• pp.571-577
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• 2015

In the paper, we propose a method for developing a physical training management module which sends physical data to smart devices using an wireless module attached to physical appliances. In the proposed stick-type physical appliance, the physical amount of data measured from sensors inside the appliance is sent to a smart device via wireless communication. And then the smart device records the physical amount of data categorized in person-based data and shows useful information about the user's physical training on the dedicated display. For the performance evaluation, indoor environment and electro magnetic wave tests are taken from national specialized organizations, and their results was very efficient. The proposed physical training management module is highly extensible since it is easily applicable to other physical appliances and useful to both Android and iOS platforms.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.4
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• pp.329-332
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• 2017

In this study, a performance evaluation was carried out to develop a new add-on device with an algorithm for automatically measuring the exercise weight and repetitions when using an existing fitness machine. The developed device was designed to be simply attached to an exercise machine to measure the exercise weight and repetitions. The measured data are transferred to a smartphone using Bluetooth. As result, it is possible to detect the weights and repetitions from three users with different exercise habits with little error. The system can measure the user's motion and transfer the data to various devices capable of utilizing the workout data, giving it the advantage of being applicable to personalized health care and rehabilitation therapy.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.11
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• pp.907-914
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• 2014

The objective of this study was to increase the generating efficiency of concentrated photovoltaics (CPV) by using hybrid solar tracking. Further, the proposed system was demonstrated to have the ability to extract thermal energy from a concentrated photovoltaic system by using thermal absorbers containing heat pipe, which could then be used for a heating system or hot-water supply. The average electrical efficiency was 16 during the day, and the average thermal efficiency was 62. Therefore, this system demonstrated a total efficiency (electrical thermal) of 78. All the processes, i.e., tracking of the sun, calculation of the sun's position, reinstatement of the heating device toward the east for tracking on the next day, and system shutdown, were programmed using Simulink. A parametric analysis of the heat pipe, concentration ratio, and inlet velocity was also performed in terms of the operating temperature of the CPV and the outlet temperature. The simulation and experimental results for the thermal absorber were found to be in good agreement.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.12
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• pp.971-974
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• 2014

A ventricular assist device (VAD) is used for bridge to heart transplantation and heart diseases. Knowing the status of a pneumatic pulsatile VAD when implanting it into the body is important: when the velocity of blood flow through the VAD is slow, a thrombus may occur, and thrombosis can be fatal to a patient. In order to determine the state of a VAD, various sensors need to be implanted. Because this introduces the risk of infection and difficulties with sensor management, we developed a method for estimating the state of a VAD indirectly via the pressure in an air tube that can be measured in vitro. We compared the measured values to in vitro experimental results. The estimated and measured values showed some errors, but the accuracy can be improved by refining the estimation process to minimize the risk of infection.

• Journal of Institute of Convergence Technology
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• v.3 no.2
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• pp.11-15
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• 2013

These days, the quality of goods is required to improve in the process of manufacturing the semiconductor through the short working hours and clean transportation. The non-contact transport device using magnetic levitation can be a solution in the manufacturing process. The non-contact transport device, using electromagnetic actuation, is the system that can actually transport them by only using attraction force from the electromagnetic source without authentic contact. Moreover, the system using electromagnetic force has a substantial number of benefits ranging from unrestricted design to unlimited expansion. Especially, the price is competitive. The non-contact transport device, using electromagnetic force, has another merits in controlling by giving the same amount of attraction force to ferromagnetic body. By controlling the currents given to coil, the operator is able to decide the direction of the transportation. In order to design the optimal system, we implemented five different things such as the presence of the links below the electromagnetic, the electromagnet changes due to coupling method, the change according to the thickness of the links below electromagnet, due to changes in between electromagnetic distance direction, and the size of the current. Through simulations and the optimum design, it seems to control easily and figure out the exact size of power. It might definitely be the non-contact transport that can sharply reduce tiny scratches and particles in the process of manufacturing the semiconductor.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.1
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• pp.80-88
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• 2018

The function of a vehicle holding device (VHD) is to securely hold a launch vehicle on the launch pad and release the launch vehicle at maximum thrust after engine ignition to allow lift-off of the launch vehicle. During the release of the launch vehicle, to prevent the Ka doing a doing a doing mode, which is the vertical oscillation of the entire liquid propellant, the release of the launch vehicle should be gradual. In this study, for the gradual release of a launch vehicle, a hydraulic system comprising an accumulator and pyro valve to operate a hydraulic cylinder and control the speed of the cylinder with an orifice is introduced. Through a test, the influence of design variables on the cylinder speed is analyzed. Based on this, the design values of the hydraulic cylinder are determined. Through this study, the engineering basis for developing a VHD releasing a launch vehicle at maximum thrust is provided.