• Journal of rehabilitation welfare engineering & assistive technology
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• v.11 no.1
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• pp.63-71
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• 2017

In this paper, a signal processing circuit for semi-implantable middle ear hearing device is designed using the TCBT which is recently proposed for a new middle ear transducer that can be implanted at round window of cochlea. The designed semi-implantable hearing device transmits digital sound signal from external device located at behind the ear to the internal device implanted under the skin using inductive coupling link methods with high efficiency. The coils and signal processing circuits are designed and implemented considering the total transmission and reception distance including skin thickness of temporal bone for the semi-implantable hearing device. And also, to improve the data transmission efficiency, the output circuits which can supply sufficient signal power is designed. In order to confirm operation of semi-implantable hearing device using inductive coupling link, the circuit analysis was performed using PSpice, and the performance was verified by implementing a signal processing board of an available size.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.5
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• pp.899-906
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• 2017

This paper proposes an inter-floor noise prevention system using an open-source controller. In the proposed system, Arduino which is a widely used open source controller analyzes sound signals and vibration signals with fast fourier transform. When the magnitude of the band-passed signal excesses the noise reference considering transmission loss of a panel or a wall, the system displays warning messages on an LCD module and a mobile device for users to be aware of the noise condition. In the experiment, the system has succeeded extracting and processing the band-passed signals between 130 Hz ~ 1040 Hz. When the magnitude of the extracted signal that is subtracted from the transmission loss exceeds 45 dB, the system has displayed the warning message on an LCD module and a mobile devicefor noise reduction.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.5
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• pp.432-439
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• 2015

MEMS solid thruster module is composed of solid thruster and its control board. It was developed for the purpose of an academic research. Therefore, thermo-mechanical design and verification for space usage were not considered in the design phase. To mount it on a cube satellite without any design modification, technical efforts at the system level structure design is required. In this study, we proposed a structural design concept to mount the MEMS thruster module by using brackets for guaranteeing structure safety under launch loads and easier mating and de-mating of MEMS thruster module during test phase. The effectiveness of the design has been verified through structural analysis and vibration test. In addition, electrical connection method using spring pins between MEMS thruster and control board is effective for guaranteeing the structural safety under launch vibration loads.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.6
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• pp.432-439
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• 2020

Brake judder has been identified in some operating military units of Korean Light Tactical Vehicles(KLTV) with In-board brake systems to improve braking performance. Severe vibration generated while driving the vehicle may reduce the KLTV's driving stability and further lead to accidents. For the prevention of this, this study analyzes the root cause through the failure analysis on the vehicles with the brake judder identified. Furthermore, the improvement factor was derived by identifying a vibration transmission path by analyzing the vibration transmission mechanism. The study analysis confirmed that the vibration of the frame during braking in the tactical vehicle is a cold judder phenomenon, which is caused by an increase in disk thickness variation due to rust and foreign substances under excessive brake disc's run-out. In addition, it was confirmed that such vibration can be reduced by improving the mounting structure. So, an improvement method for each factor was suggested and its effectiveness was verified by comparison test. Finally, it is expected that the improvement plans derived through this study can be used in the development of a next military vehicle.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.2
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• pp.225-231
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• 2012

Drop simulations of the board level in the flip chips with solder joints have been highlighted for years, recently. Also, through the study on the life prediction of thermal fatigue in the flip chips considering underfill, its importance has been issued greatly. In this paper, dynamic analysis using the implicit method in the Finite Element Analysis (FEA) is carried out to assess the factors effecting on flip chips considering underfill. The design parameters are size and thickness of chip, and size, pitch and array of solder ball with composition of Sn1.0Ag0.5Cu. The board systems by JEDEC standard is modeled with various design parameter combinations, and through these simulations, maximum yield stress and strain at each chip are shown at the solder balls. Modal analysis is simulated to find out the relation between drop impact and vibration of the board system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.11
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• pp.51-56
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• 2016

In this paper, we propose an Arduino-based plant monitoring system. The proposed system is based on the Arduino platform, using an environmental sensor and a pressure sensor for measuring temperature, humidity and illuminance in order to monitor the state of the environment and the facilities of the plant. Monitoring data are transmitted to a ZigBee coordinator connected to a server through a radio frequency transceiver. When using a pressure sensor and the environment sensor data stored on the host server, checking the pressure in the environment of the plant and equipment is intended to report any alarm status to the administrator. Using a grid line-based key distribution scheme, the authentication node dynamically generates a data key to protect the monitoring information. Applying a ZigBee wireless sensor network does not require additional wiring for the actual implementation of a plant monitoring system. Possible working-environment monitoring of an efficient plant can help analyze the cause of any failure by backtracking the working environment when a failure occurs. In addition, it is easy to expand or add a sensor function using the Arduino platform and an expansion board.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.49 no.8
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• pp.16-21
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• 2012

The gyro sensor that made by MEMS process is generated an accumulated error(drift) and escape the zero angle following during calculation of rotate angle. This study propose BACF(Boot Angle Compensation Filter) algorithm for prevent escape zero angle and DCF algorithm for remove accumulated error. DCF algorithm is designed for acquire accurate turn of ratio by remove offset and noise components. BACF algorithm is obtained average offset that removed noise components by recursively calculate. Experimental environment, two-axis gyro sensor and mobile OIS camera mounted control board and 5Hz oscillation of ${\pm}0.5^{\circ}$ for the experiments were carried out. BACF and DCF algorithm is applied and the resulting accumulated error did not occur and exactly zero angle following results were made.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.6
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• pp.431-441
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• 2020

In this paper, we propose a new method using a feedforward disturbance observer that guarantees stability and robustness about the effects of external disturbance and model uncertainty. The method is consist of a disturbance observer, a feedforward controller, and an overshoot detecting logic. It has an advantage of reducing the excessive overshoot by external disturbance and model uncertainty. Also, it is easy to adjust the control gain due to a simple structure. In order to verify the effectiveness of a new method, simulation results are given for longitudinal model of F-16 aircraft. By reflecting a various of model uncertainties, the stability and the robustness are guaranteed. Finally, the stability and the robustness of the proposed method are verified using root locus plot and bode plot.

• Journal of the Microelectronics and Packaging Society
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• v.17 no.4
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• pp.35-40
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• 2010

In this study, the reliability of thermal shock, thermal cycle, and complex vibration test at high temperature were examined for 3 types of lead-free solder alloys, Sn-3.5Ag, Sn-0.7Cu and Sn-5.0Sb. For the reliability test, daisychained BGA chips with ENIG-finished Cu pad was assembled with the three lead-free solders on OSP-finished PCBs. Among the 3 types solder alloys, Sn-3.5Ag solder alloy showed the highest degradation rate of electrical resistance and joint strength. On the other hand, Sn-0.7Cu solder alloy had high stability after the reliability tests.

• Journal of the Institute of Convergence Signal Processing
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• v.10 no.1
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• pp.86-92
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• 2009

As increasing of using induction motors, the induction motors faults cause serious damage to the industry. Therefore to find out faults of induction motor is recognized as important problem awaiting solution. But to make matters worse, the faults of induction motors often progress through long time. It means that early diagnosis is very important. Many researches have been progressed and general method of diagnosis is using vibration sensor to diagnose fault of induction motor. However, although it is reliability technique, it demands high price and it is difficult to use. This paper presents an implementation of technique for fault diagnosis of induction motor using wavelet transform based stator current and it is composed with algorithm that decides whether fault existence or not using C++ based on windows software. The algorithm will be accomplished in real-time using current data acquisition board and PC automatically with Neural Network algorithm.