• International Journal of Aeronautical and Space Sciences
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• v.16 no.2
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• pp.190-205
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• 2015

In this paper, the impact damage behavior of USN-150B carbon/epoxy composite laminates subjected to high velocity impact was studied experimentally and numerically. Square composite laminates stacked with $[45/0/-45/90]_{ns}$ quasi-symmetric and $[0/90]_{ns}$ cross-ply stacking sequences and a conical shape projectile with steel core, copper skin and lead filler were considered. First high-velocity impact tests were conducted under various test conditions. Three tests were repeated under the same impact condition. Projectile velocity before and after penetration were measured by infrared ray sensors and magnetic sensors. High-speed camera shots and C-Scan images were also taken to measure the projectile velocities and to obtain the information on the damage shapes of the projectile and the laminate specimens. Next, the numerical simulation was performed using explicit finite element code LS-DYNA. Both the projectile and the composite laminate were modeled using three-dimensional solid elements. Residual velocity history of the impact projectile and the failure shape and extents of the laminates were predicted and systematically examined. The results of this study can provide the understanding on the penetration process of laminated composites during ballistic impact, as well as the damage amount and modes. These were thought to be utilized to predict the decrease of mechanical properties and also to help mitigate impact damage of composite structures.

• Journal of KIISE:Software and Applications
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• v.36 no.11
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• pp.920-927
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• 2009

In this paper, we developed a system that could assist appropriate activities for medication compliancy of the elderly. It employs a proactive knowledge which is represented as XML templates predefined for their medication activities. The knowledge-based assistance depends on the contexts considerably, which the system can recognize by continuously monitoring the current position and the time-schedule for their medications. The monitoring can be performed with ultrasonic sensors and infrared sensors mounted in a display and a pillbox respectively. According to the recognized contexts, the medication activities required by the elderly can be serviced through user-friendly multimedia display. In special, our experiment evaluates that the developed system is able to enhance the medication compliancy of chronic disease patients.

• Journal of Sensor Science and Technology
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• v.11 no.4
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• pp.247-253
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• 2002

For fabrication of the pyroelectric IR sensor $(Pb,La)TiO_3(PLT)$/$LiTaO_3$/(LTO)/PLT ferroelectric thin films was deposited by rf magnetron sputtering followed by rapid thermal annealing and the crystallinity as a function of annealing temperature and time was investigated. Permittivity and dielectric loss factor of ferroelectric thin films as a function of c-axis preffered orientation was measured. Also pyroelectric coefficient of ferroelectric thin films with largest c-axis preffered orientation was measured and obtain figure of merit of voltage response($F_V$) and detectivity($F_D$). In this case $F_V$, $F_D$ was $5.63{\times}10^{-10}\;C{\cdot}cm/J$, $1.98{\times}10^{-8}\;C{\cdot}cm/J$, respectively.

• Journal of The Korean Society of Agricultural Engineers
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• v.62 no.5
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• pp.85-91
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• 2020

In order to calculate the Crop Water Stress Index (CWSI), it is necessary to collect weather data (air temperature, humidity, wind speed and solar radiation) and canopy temperature. However, it is not always available to have necessary data sets for CWSI calculation. Therefore, this study was aimed to develop an easy and simple CWSI equation (CWSI_EE) using only two data, air and canopy temperatures. Infrared sensors and weather sensors were installed on apple and peach trees and nearby a study area and every ten-minute data were collected from June to October in 2018 and 2019, respectively. A relationship between air-canopy temperature difference and CWSI was statistically analyzed and used to develop CWSI_EE using the three dimensional Gaussian model. The performance of CWSI_EE against original CWSI showed R² and NSE to 0.780 and 0.710 for apple trees and R² and NSE to 0.884 and 0.866 for peach trees. This study found that the level of crop water stress could be easily calculated using CWSI_EE with only air and canopy temperature data.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.558-561
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• 2018

Human errors have known as a majority of maritime navigational accidents such as collision and grounding. A large number of relevant research applied indirect research methods such as survey and interview. The research methods are limited to collect objective data regarding human errors due to its nature. Therefore, the purpose of this study is to improve the limitation of human error measurement of navigators by applying wearable sensors. Infrared sensors by using a 3-D printer to accommodate the special environment of a ship were developed for the study. As results, a significant reliance on the Integrated Navigation System including Electronic Chart Display and Information System (ECDIS) and Radar. The results are expected to motivate further research to investigate human errors of ship navigators to reduce the maritime navigational accidents.

• Journal of Sensor Science and Technology
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• v.5 no.3
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• pp.87-92
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• 1996

The PLT thin films on (100) cleaved MgO single crystal substrate have been fabricated by rf magnetron sputtering using a PbO-rich target. The dependence of physical and electrical properties on the degree of c-axis orientation has been studied. The degree of c-axis orientation of PLT thin films depends on fabrication conditions. Fabrication conditions of the PLT thin films were such that substrate temperature, working pressure, gas ratio of $Ar/O_{2}$, and rf power density were $640^{\circ}C$, 10 mTorr, 10 seem, and $1.7\;W/cm^{2}$, respectively. In these conditions, the PLT thin film showed the Pb/Ti ratio of 1/2 at the surface, the resistivity of $8{\times}10^{11}{\Omega}{\cdot}cm$, and dielectric constant of 110. The pyroelectric infrared sensors with these PLT thin films showed the peak to peak voltage of 450 m V and signal to noise ratio of 7.2.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.725-728
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• 2009

This paper describes remote monitoring system for the various environments of a vinyl house, which was located in rural or outer of urban by use internet web connection system in a long distance office. We have constructed remote monitoring system by use a simple experimental model for the monitoring of various factors which need to operate common vinyl house. The experimental model includes temperature, humidity, smoke and infrared sensors for the measuring and AC 220V light bulb for the controlling in the USN system. Also, we have developed monitoring software by use NI Labview and communicate between PC and sensors through the DAQ-board, USN control board. We use CCD camera and grab board for the real time remote monitoring of wanted image in the house area. The computer server for remote connection is constructed in the local PC with Apache web server, PHP and MySQL ODBC. We construct internet communication system for the monitoring remotely the local environments of a vinyl house system.

• Journal of Sensor Science and Technology
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• v.30 no.5
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• pp.342-348
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• 2021

For the characterization or failure analysis of electronic devices such as PCB (printed circuit boards), the most common method is the measurement of voltage waveforms with an oscilloscope. However, because there are many types of problems that cannot be detected by voltage waveform analysis, several other methods such as X-ray transmission, infrared imaging, or eddy current measurement have been applied for these analyses. However, these methods have also been limited to general analyses because they are partially useful in detecting physical defects, such as disconnections or short circuits. Fundamentally current waveform measurements during the operation of electronic devices need to be performed, however, commercially available current sensors have not yet been developed, particularly for applications in highly integrated PCB products with sub-millimeter fine pitch. In this study, we developed a highly sensitive PHR (planar hall resistance) magnetic sensor for application in highly integrated PCBs. The developed magnetic sensor exhibited sufficient features of an ultra-small size of less than 340 ㎛, magnetic field resolution of 10 nT, and current resolution of 1 mA, which can be applicable for PCB analyses. In this work, we introduce the development process of the magnetic sensing probe and its characteristic results in detail, and aim to extend this pin-type current probe to applications such as current distribution imaging of PCBs.

• Journal of IKEEE
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• v.22 no.4
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• pp.922-932
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• 2018

Radial distance sensors are widely used for surveying and autonomous navigation. It is necessary to train the operation principle of these sensors and how to apply them. Although commercialization of radial distance sensor continues to be cost-effective through lower performance, but it is still expensive for educational purposes. In this paper, we propose a distance sensor module with object tracking using radial array of low cost phototransistor which can be used for educational robot. The proposed method is able to detect the position of a fast moving object immediately by arranging the phototransistor in the range of 180 degrees and improve the sensing angle range and track the object by the sensor rotation using the servo motor. The scan speed of the proposed sensor is 50~200 times faster than the commercial distance sensor, thus it can be applied to a high performance educational mobile robot with 1ms control loop.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.10
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• pp.1361-1368
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• 2020

The system for counting the number of people has traditionally been implemented in various ways. Existing systems include infrared sensors, lasers, cameras, etc. In the case of such an existing system, there are restrictions on space such as ceilings and sides of walls. In this paper, we propose a method of detecting the footsteps of pedestrians using a piezoelectric mat containing a number of piezoelectric sensors and counting the number of pedestrians passing simultaneously by using the data collected from the piezoelectric mat. When pedestrians pass over piezoelectric mats, the collected sensor data was aggregated using SPI communication and transmitted to PC server using TCP/IP communication. Performance analysis shows that approximately 600 step data can be recognized with 99% accuracy. This is to overcome the shortcomings of other counting systems.