• Journal of the Korean Vacuum Society
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• v.17 no.5
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• pp.448-454
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• 2008

The purpose of this paper is to discuss the fabrication of $\beta$-PVDF($\beta$-Polyvinylidene fluoride, ${\beta}-PVF_2$) organic thin films through the vapor deposition method and to investigate the piezoelectric properties of the organic thin films produced. Vapor deposition was performed under the following conditions : the temperature of evaporator, the applied electric field and the pressure of reaction chamber were $270^{\circ}C$, 142.4 kV/cm and $2.0{\times}10^{-5}Torr$, respectively. The results showed that the amount of $\beta$-form PVDF increased from 72 % to 95.5 % with an increase in the substrate temperature. In the case of a sensor response characteristic by varying the force moment from $1.372{\times}10^{-5}N{\cdot}m$ to $39.2{\times}10^{-5}N{\cdot}m$, the output voltage increased from 1.39V to 7.04V.

• Composites Research
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• v.27 no.4
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• pp.146-151
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• 2014

In this study, the experimental study has been performed by varying the polarization of the electric field and impact force to check the piezoelectric characteristics of piezoelectric paint sensor. Piezoelectric paint sensor used in this study is composed of epoxy resin with a hardener and PNN-PZT powder in 1:1 weight ratio. The dimensions of the paint sensor specimen are $40{\times}40{\times}1mm^3$ and regular specimens were made using a mold. The voids are removed from the specimen in the vacuum desiccator. Both upper side and bottom side of the paint sensor were coated with silver paste for making an electrode and then dried at room temperature for a day. The poling treatment has been carried out under controlled conditions of the electric field in order to check the effect of piezoelectric sensitivities, while the poling temperature was fixed at room temperature and the poling time was set to 30 min. The piezoelectric sensitivities have been measured by comparing output voltage from paint sensor with output force from impact hammer when the impact hammer hits the paint sensor. In result, the effect of the electric field has been evaluated for the sensitivity and describe the result.

• 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 Institute of Information and Communication Engineering
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• v.21 no.4
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• pp.836-845
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• 2017

Due to the development of endoscopic technology, endoscopic diagnosis and procedures have been actively performed. However, due to the increase in colorectal cancer and the effect of government's early cancer screening project, the number of endoscopic diagnosis and procedures has increased, thus medical accidents such as perforation and bleeding are increasing. Therefore, efforts to reduce such medical accidents are needed. In this paper, we propose a method to provide the direction information of the endoscope and the force applied to the probe in real time. We also propose and evaluate an interpolated complementary filter considering the very slow movement of the endoscope probe. The proposed interpolated complementary filter showed 34.6% and 27.6% performance improvement. The expected user interface for applying the proposed method to the endoscopic system is also presented. This shows that the proposed method is applicable to endoscopy system.

• The Journal of Korean Physical Therapy
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• v.12 no.2
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• pp.29-37
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• 2000

본 연구의 목적은 힘판(Force plate)의 지면반발력(Ground reaction force)의 비교에 따라 발압력 측정계(F-메트와 F-스킨)의 상호 기계간의 신뢰성과 타당성을 연구하는 데에 목적을 두고 있으며 정상인과 리스프랑크(Lisfranc) 골절을 가지고 있는 환자를 대상으로 분석 연구하게 되었다. 힘판의 지면 반발력을 기준치로 설정하고 정상인과 환자의 각각 오른발과 왼발의 스텝에 대해 F 메트(F-mat) 와 F 스캔(F-scan) 시스템의 그래픽 비교 모식과 시간에따른 보령분석의 차이에 따라 이 논문에 대한 결과를 얻을 수 있었다. 본 연구에서는 F 스킨 시스템의 데이터 분석기인 새로운 버전 3.622와 마이크로 소프트웨어인 엑셀 97을 통해 새 시스템의 힘의 평균치와 그래픽을 통해 비교 분석하게 되었으며 다음과 같은 세가지 결론을 얻을 수 있었다. 첫 번째로 F스캔의 지면 반발력은 힘판과 비교되어질 때 통계학적으로 중요한 차이점을 얻을 수 없을 것이다. 두 번째, F 메트를 위한 지면 반발력 역시 힘판과 비교되어질 때 통계학적으로 중요한 차이점율 얻음 수 없을 것이다. 세 번째로 정상군과 실험군의 지면 반발력에 대해 중요한 차이점이 있을 것이라는 것이 밝혀졌다. 특히 정상군의 대상자는 실험군의 대상자와 비교되어질 때 각 발에 대해 증가된 지면 반발력을 나타내었다. 이상 본 연구에 대해 다음의 결론을 내릴 수가 있었고 기존의 F 스캔 시스템이 임상적으로 많이 쓰여졌지만 F 스캔의 센서에 대해 많은 이견 차이를 보였었다. 한편. F메트 시스템에서 F메트 센서의 일관성에 대해서는 어느 연구 논문도 나오지 않았고 이에 대해 F스캔(F-scan)과 힘판(Force plate)를 상호 비교하여 F메트 시스템에 대한 신뢰성과 타당성을 연구하는데 목적을 두게되었다.

• Journal of the Korean Society for Railway
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• v.18 no.4
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• pp.335-343
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• 2015

The role of the turnouts installed on the points of railway branches and intersections is to safely switch the directions of trains. In case of abnormal forces applied to the turnouts due to extreme operating conditions, it is difficult in the current system to conduct accurate diagnosis and measuring. Moreover, the existing measurement devices for turnout switching power are mostly based on foreign technologies, which provide only limited information on the switching power; this information is insufficient for effective monitoring and maintenance. In this paper, through an analysis of the characteristics of the switching and locking function, the problems in turnout power measurements of current electrical point machines in Korea are examined. And based on the results, a new sensor-based method for measuring switching power is proposed.

• Journal of Korea Game Society
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• v.14 no.2
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• pp.67-76
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• 2014

Recently there have been many interests on tangible sport games that can recognize the motions of players. In this paper, we propose essential technologies required for tangible games, which are methods for swing motion recognition and the calculation of shuttle cock's trajectory. When a user carries out a badminton swing while holding a smartphone with his hand, the motion signal generated by smartphone-embedded acceleration sensors is transformed into a feature vector through a Daubechies filter, and then its swing type is recognized using a k-NN based method. The method for swing motion presented herein provides an advantage in a way that a player can enjoy tangible games without purchasing a commercial motion controller. Since a badminton shuttle cock has a particular flight trajectory due to the nature of its shape, it is not easy to calculate the trajectory of the shuttle cock using simple physics rules about force and velocity. In this paper, we propose a method for calculating the flight trajectory of a badminton shuttle cock in which the wind effect is considered.

• Journal of Sensor Science and Technology
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• v.5 no.5
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• pp.55-62
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• 1996

This paper describes development of Polarized Stereo Monitoring System (KAERI-PSM) and compares the remote handling performance of KAERI-PSM with that of other monitoring systems, electric shutter type stereo monitoring system and general TV monitoring system. Remote handling performance is evaluated by total time and error number on remote operating experiments. Four kinds of remote handling experiments are carried out through 1) directly 2) general TV 3) electric shutter type monitor, and 4) KAERI-PSM. In these experiments six employees are participated and PUMA robot with force-torque reflectional joystic is used. The result of experiments show that camera angle against object is significant factor in monitoring and stereo monitoring system give more performance benifits in terms of accuracy and speed of remote handling operation than general TV monitoring system. In comparision of the polarized and electric shutter type stereo monitoring system, both have similar accuracy and speed for remote handling operation, but the former is superior in image quality and stability of the performance.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.48 no.6
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• pp.63-70
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• 2011

A bicycle is different from vehicles in the structure that a rider is fully exposed to the surrounding environment. Therefore, it needs to make use of prior information about local weather, air quality, trail road condition. Moreover, since it depends on human power for moving, it should acquire route property such as hill slope, winding, and road surface to improve its efficiency in everyday use. Recent mobile applications which are to be used during bicycle riding let us aware of the necessity of development of intelligent bicycles. This study aims to develop a riding state (up-hill, down-hill, accelerating, braking) recognition algorithm using a low-power wrist watch type embedded system which has 3-axis accelerometer and wireless communication capability. The developed algorithm was applied to 19 experimental riding data and showed more than 95% of correct recognition over 83.3% of the total dataset. The altitude and temperature sensor also in the embedded system mounted on the bicycle is being used to improve the accuracy of the algorithm. The developed riding state recognition algorithm is expected to be a platform technology for intelligent bicycle interface system.

• Proceedings of the KIEE Conference
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• 2008.04a
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• pp.236-237
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• 2008

이 논문은 노인 및 장애인의 활동을 보조하기 위한 보행보조 로봇의 핵심 기술인 사용자의 진행하고자 하는 방향과 속도를 검출하는 보행의지 파악시스템 구현을 하고자 한다. 최근에 노인인구의 증가로 인해 노인 및 장애인을 위한 보행 보조기에 대한 관심이 증가되고 있다. 그러나 대부분의 경우 동력이 없는 시스템으로 경사 등의 공간에서 취약성을 가지고 있다. 이에 동력형 보행보조기에 대만 관심이 증가되고 있으나, 대부분의 경우 보행보조기 조종이 여의치 않다. 이에 본 논문에서는 사용자의 보행의지를 파악할 수 있는 시스템을 도입하고 이를 기초로 보행자의 안정적인 구동을 수행할 수 있도록 하였다. 사용자의 의지력은 FSR 센서를 이용하여 파악하고, 이를 기초로 사용자가 이동하고자 하는 이동 방향과 이동속도 데이터를 기초로 보행보조기의 차량 속도와 방향에 대해 구동 바퀴의 차동구동을 통해 사용자의 의지에 맞춰 구동할 수 있도록 하였다. 이를 통해 사용자의 이동하려는 의지에 대해 안정적으로 차량을 이동시킬 수 있도록 보행 시스템을 구축하였다. 또한 사용자자의 힘에 대한 속도 및 방향 매핑 기법을 개발하여 보행의지의 정확성을 높였다.