• Journal of the Korean Society of Radiology
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• v.17 no.6
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• pp.859-863
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• 2023

In this study, simple and portable radiation detection system using X-ray intensifying screen, optical sensor and micro-controller unit for education was proposed. The system was simply composed of detection unit consisting of an optical sensor and intensifying screen, micro-controller unit, and was designed to be suitable for portable. Radiation was measured using developed detection system and absorbed dose dosimeter with changing tube voltage from 50 to 100 kVp. The tube current and SDD were fixed on 100 mAs and 100 cm, and dose were measured repeated ten times at each tube voltage. The response and linearity of the detection system were confirmed using the measured values. It was confirmed that the comparison measurement results of the detection system and absorbed dose dosimeter showed a high correlation(r : 0.998, p<.001). In this results, the feasibility of the detection system with intensifying screen and micro-controller unit based was confirmed, and we considered that the developed detection system could be applied to portable, compact, low cost system for education.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.295-296
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• 2006

We developed wire frame drive unit based on SMA for the 3D Shape display. Our basic concept is wire frame combination connected with a chain form which can create various shapes and it compared with pin array mechanism which is not able to display mushroom shape. It imitates antagonist mechanism of human musculoskeletal system. we create similar motion using repair-relaxation mechanism and locking mechanism by SMA. Therefore, in this paper, we propose SMA control solution for actuating repair-relaxation mechanism and locking mechanism. In our control system. we use optical sensor and quantitative angle between wire frames for closed loop control. And we supply amplified current for SMA by circuit composed of transistor and apply PWM signal to circuit for efficient control. So, wire frame drive unit enable diversity angle control based on sensor data. And then combination of wire frame drive units will create various objects.

• Journal of IKEEE
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• v.1 no.1 s.1
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• pp.1-10
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• 1997

It is well-known that rectangular bulk-Si sensors prepared by etch or epi etch-stop micromachining technology are already in practical use today, but the conventional bulk-Si sensor shows some drawbacks such as large chip size and limited applications as silicon sensor device is to be miniaturized. We consider a circular-shape SOI(Silicon-On-Insulator) micro-cavity technology to facilitate multiple sensors on very small chip, to make device easier to package than conventional sensor like pressure sensor and to provide very high over-pressure capability. This paper demonstrates the cross-functional results for stress analyses(targeting $5{\mu}m$ deflection and 100MPa stress as maximum at various applicable pressure ranges), for finding permissible diaphragm dimension by output sensitivity, and piezoresistive sensor theory from two-type SOI structures where the double SOI structure shows the most feasible deflection and small stress at various ambient pressures. Those results can be compared with the ones of circular-shape bulk-Si based sensor$^{[17]}. The SOI micro-cavity formed the sensors is promising to integrate with calibration, gain stage and controller unit plus high current/high voltage CMOS drivers onto monolithic chip.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.46 no.4
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• pp.42-49
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• 2009

This paper proposes a driving current control method for a back light unit (BLU), consisting of red, green, and blue (RGB) light-emitting diodes (LEDs), whereby an RGB optical sensor is used to check the output color stimulus variation to enable a time-stable color stimulus for light emission by the RGB LED BLU. First, to obtain the present color stimulus information of the RGB LED BLU, an RGB to XYZ transform matrix is derived to enable CIEXYZ values to be calculated for the RGB LED BLU from the output values of an RGB optical sensor. The elements of the RGB to XYZ transform matrix are polynomial coefficients resulting from a polynomial regression. Next, to obtain the proper duty control values for the current supplied to the RGB LEDs, an XYZ to Duty transform matrix is derived to calculate the duty control values for the RGB LEDs from the target CIEXYZ values. The data used to derive the XYZ to Duty transform matrix are the CIEXYZ values for the RGB LED BLU estimated from the output values of the RGB optical sensor and corresponding duty control values applied to the RGB LEDs for the present, first preceding, and second preceding sequential check points. With every fixed-interval check of the color stimulus of the RGB LED BLU, the XYZ to Duty transform matrix changes adaptively according to the present lighting condition of the RGB LED BLU, thereby allowing the RGB LED BLU to emit the target color stimulus in a time-stable format regardless of changes in the lighting condition of the RGB LEDs.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.585-588
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• 2014

This paper presents a self-powered sensor node circuit using photovoltaic and vibration energy harvesting. The harvested energy from a solar cell and a vibration device(PZT) is stored in a storage capacitor. The stored energy is managed by a PMU(Power Management Unit). In order to supply a stable voltage to the sensor node, an LDO(Low Drop Out Regulator) is used. The LDO drives a temperature sensor and a SAR ADC(Successive Approximate Register Analog-to-Digital Converter), and 10-bit digital output data corresponding to current temperature is obtained. The proposed circuit is designed in a 0.35um CMOS process, and the designed chip size including PADs is $1.1mm{\times}0.95mm$.

• Agricultural and Biosystems Engineering
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• v.5 no.1
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• pp.10-20
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• 2004

Precision agriculture aims to minimize costs and environmental damage caused by agriculture and to maximize crop yield and profitability, based on information collected at within-field locations. In this process, quantification of soil physical properties, including soil strength, would be useful. To quantify and manage variability in soil strength, there is need for a strength sensor that can take measurements continuously while traveling across the field. In this paper, preliminary analyses were conducted using two datasets available with current technology, (1) cone penetrometer readings collected at different compaction levels and for different soil textures and (2) tillage draft (TD) collected from an entire field. The objective was to provide information useful for design of an on-the-go soil strength profile sensor and for interpretation of sensor test results. Analysis of cone index (CI) profiles led to the selection of a 0.5-m design sensing depth, 10-MPa maximum expected soil strength, and 0.1-MPa sensing resolution. Compaction level, depth, texture, and water content of the soil all affected CI. The effects of these interacting factors on data obtained with the soil strength sensor should be investigated through experiments. Spatial analyses of CI and TD indicated that the on-the-go soil strength sensor should acquire high spatial-resolution, high-frequency ($\ge$ 4 Hz) measurements to capture within-field spatial variability.

• Current Optics and Photonics
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• v.4 no.3
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• pp.186-192
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• 2020

This paper describes a real-time monitoring system in Ethernet passive optical networks (EPON) that uses burst-mode fiber Bragg grating (FBG) optical sensors. The FBG interrogation unit in the optical line terminal (OLT) transmits the monitoring wavelength to optical network units (ONUs). The FBG sensor unit in each ONU returns a burst-mode monitoring signal to the OLT. As the system applies time division multiple access (TDMA), a uniform Bragg wavelength can be used to monitor the EPON system. The FBG interrogation unit analyzes the received burst-mode monitoring signals and outputs fault information on the ONU branches in EPON. The simulation results show the effectiveness of the proposed monitoring system based on TDMA. In addition, we compared the proposed TDMA-based monitoring system with a WDMA-based monitoring system.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.783-788
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• 2005

Detection of small leakage current is the most important technique in arrester diagnosis. Various types of leakage current detector have been commercialized, but they are not available for the railway arresters including voltage harmonics, and do not furnish enough information needed for arrester diagnosis. This paper describes the development of a leakage current detector which is suitable for the railway arresters. The detector is consisted of a sensor unit with amplifier, an optical linker and main analyzer. Frequency bandwidth and measuring range of the detector is 9[Hz]$\~$850[Hz] and 50[uA]$\~$5[mA], respectively.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.571-574
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• 2008

In this paper, we propose $256{\times}256$ pixel array fingerprint sensor with an advanced circuits for detecting. The pixel level simple detection circuit converts from a small and variable sensing current to binary voltage out effectively. We minimizes an electrostatic discharge(ESD) influence by applying an effective isolation structure. The sensor circuit blocks were designed and simulated in standard CMOS $0.35{\mu}m$ process. Full custom layout is performed in the unit sensor pixel and auto placement and routing is performed in the full chip.

• Journal of the Korea Society of Computer and Information
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• v.28 no.1
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• pp.49-54
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• 2023

The Global Positioning System (GPS) was developed for military purposes and developed as it is today by opening civilian signals (GPS L1 frequency C/A signals). The current satellite orbits the earth about twice a day to measure the position, and receives more than 3 satellite signals (initially, 4 to calculate even the time error). The three-dimensional position of the ground receiver is determined using the data from the radio wave departure time to the radio wave Time of Arrival(TOA) of the received satellite signal through trilateration. In the case of navigation using GPS in recent years, a location error of 5 to 10 m usually occurs, and quite a lot of areas, such as apartments, indoors, tunnels, factory areas, and mountainous areas, exist as blind spots or neutralized areas outside the error range of GPS. Therefore, in order to acquire one's own location information in an area where GPS satellite signal reception is impossible, another method should be proposed. In this study, IMU(Inertial Measurement Unit) combined with an acceleration and gyro sensor and a geomagnetic sensor were used to design a system to enable location recognition even in terrain where GPS signal reception is impossible. A method to track the current position by calculating the instantaneous velocity value using a 9-DOF IMU and a geomagnetic sensor was studied, and its feasibility was verified through production and experimentation.