• Journal of Sensor Science and Technology
• /
• v.26 no.5
• /
• pp.324-330
• /
• 2017

In this paper, the automation of sweeping center setting for wavelength swept laser used in SS-OCT has implemented. For 3 regions where the initial FFP-TF pass wavelength can be located, each different DC voltage pattern is applied to FFP-TF. Through its performance test to the laser, fast and exact setting to sweeping central wavelength, flat sweeping with ${\pm}0.5dB$ fluctuation range, and 10 mW average optical power were obtained. This shows that the realized automatic setting process can replace an inconvenient manual setting operation used for current wavelength swept laser. Additionally it cuts costs for optical spectrum analyzer necessary to laser spectrum monitoring.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.15 no.3
• /
• pp.349-355
• /
• 2015

A fully-differential touch-screen sensing architecture is presented to improve noise immunity and also support most multi-touch events minimizing the number of amplifiers and their silicon area. A correlated double sampling function is incorporated to reduce DC offset and low-frequency noises, and a stabilizer circuit is also embedded to minimize inherent transient fluctuations. A prototype of the proposed readout circuit was fabricated in a $0.18{\mu}m$ CMOS process and its differential operation in response to various touch events was experimentally verified. With a 3.3 V supply, the current dissipation was 3.4 mA at normal operation and $140{\mu}A$ in standby mode.

• Journal of the Semiconductor & Display Technology
• /
• v.21 no.3
• /
• pp.33-38
• /
• 2022

A solar power generation system uses a solar module that collects solar radiation energy, a connecting board that collects DC power generated from the solar module, and a diode to prevent reverse current from flowing from an inverter to the solar module. The existing photovoltaic connection module consists of only fuses and diodes for reverse polarity and overcurrent blocking, and does not have fire diagnosis, prevention, and suppression functions in the event of a fire. To solve this problem, this paper presents a method to monitor the internal state of the photovoltaic connection module using several sensors and to prevent and extinguish a fire using solenoid valves and fire extinguishing agents when a fire is detected. Through the experiment, it was confirmed that the proposed method normally suppresses the fire in event of a fire.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.40 no.4
• /
• pp.65-73
• /
• 2003

This paper presents the implementation of an analog signal-processing ASIS to detect an angular velocity signal from a vibrator angular velocity detection sensor. The output of the sensor to be charge appeared as the variation of the capacitance value in the structure of the sensor was detected using charge amplifiers and a self oscillation circuit for driving the sensor was implemented with a sinusoidal self oscillation circuit using the resonance characteristics of the sensor. Specially an automatic gain control circuit was utilized to prevent the deterioration of self-oscillation characteristics due to the external elements such as the characteristic variation of the sensor process and the temperature variation. The angular velocity signal, amplitude-mod)Hated in the operation characteristics of the sensor, was demodulated using a synchronous detection circuit. A switching multiplication circuit was used in the synchronous detection circuit to prevent the magnitude variation of detected signal caused by the amplitude variation of the carrier signal. The ASIC was designed and implemented using 0.5${\mu}{\textrm}{m}$ CMOS process. The chip size was 1.2mm x 1mm. In the experiment under the supply voltage of 3V, the ASIC consumed the supply current of 3.6mA and noise spectrum density from dc to 50Hz was in the range of -95 dBrms/√Hz and -100 dBrms/√Hz when the ASIC, coupled with the sensor, was in normal operation.

• Journal of the Korean Society of Safety
• /
• v.30 no.4
• /
• pp.39-45
• /
• 2015

This paper deals with development of integrity evaluation instrument for the power line surge protective device. A reliable power supply is an essential element in the developed information and communication society by highly advances in IT technology. However, the lightning incidence also increased with the recent extreme weather events. In Korea, in order to protect the electrical system from lightning surge, SPD(Surge Protective Device) has been used for these past 30 years. However, the method of diagnosing the safety of the SPD in the industry is insufficient. In this paper, SPD integrity evaluation system was composed of a variable DC power source unit, voltage-current sensor and the embedded controller. In order to measure V-I characteristics of MOV, 3 type samples were degraded by impulse current generator. After impulse tests, the varistor voltage of all samples and nonlinearity coefficient were decreased. It confirmed the utility of the developed equipment by this experimental test and the reliability of SPD is expected for surge accident prevention when applied to industrial plant.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.9 no.5
• /
• pp.57-63
• /
• 1995

In this paper, 3-Phase PWM AC/DC step up type converter that reduces the harmonics and reactive power of the distribution line is analyzed and the stable control method is proposed as controlling the sinusoidal phase current and phase voltage in phase. In implementation of controller, simple control algorithm is derived as the instantaneous voltage control methods without current sensor. The instantaneous voltage is controled by PWM method and the switching frequency is presented in low range 3 [kHz] for reducing the switching loss. In case of active load, four quadrants operation converter regenerate power from the load to the power source is conducted. Through the computer simulation and experimentation, the proposed control method is justified.

• Journal of the Korean Society of Safety
• /
• v.32 no.3
• /
• pp.15-20
• /
• 2017

This study presented the strength of the materials and parts for smart distribution board fabrication, and developed a work operation process chart for smart distribution board fabrication. This work operation process chart for smart distribution board fabrication complied with SPS-KEMC regulations, and the applicable range and object are less than 1,000 V and 1,000 Hz for the AC distribution board and less than 1,500 V for the DC distribution board. The power supply is 3 phase 4 wires ($3{\Phi}$ 4W), divided into a single phase circuit and a 3 phase circuit. In addition, the circuit was configured so that the leakage current flowing through the distribution line of the load could be monitored in real time by using the sensor module installed at the rear end of the circuit breaker. Therefore, the administrator can easily find the risk factor of the load since engineer can check the leakage current of each distribution line. In addition, if a leakage current greater than standard value flows, it is possible to generate an alarm against a short circuit and cut off the leakage current. The work operation process chart for the smart distribution board fabrication consists of the following steps: raw and subsidiary materials, sheet metal work, tube making, welding, painting, busbar fabrication, assembly and wiring, product inspection, shipment, etc. Moreover, symbols, ${\Delta}$, ${\nabla}$, ${\bigcirc}$, ${\Rightarrow}$, etc. were used according to the type of work and work progress so that workers can easily understand the progress of the work.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.9 no.6
• /
• pp.536-543
• /
• 2004

Slotless Permanent Magnet Brushless DC Motor(PM BLDC) with the characteristics of high speed and power density has been more widely used In Industrial and factory machine. Generally, PM BLDC meter is necessary that the three Hall-lCs evenly be distributed around the stator circumference in case of the 3 phase motor. The Hall-ICs are set up in PM BLDC Motor to detect the main flux from the rotor. therefore the output signal from Hall-ICs is used to drive a power transistor to control the stator winding current. However, instead of using three Hall-ICs, if it used only one Hall-IC, we can estimate information of the others phase in sequence through a rotor This paper identified the characteristics and performance by using one Hall-IC with the 3-phase, 2-pole, 6-slot PM BLDC motor.

• Journal of Sensor Science and Technology
• /
• v.7 no.2
• /
• pp.131-139
• /
• 1998

$CdS_{0.67}Se_{0.33}$ single crystal was grown by vertical sublimation method of closed tube physical vapour deposition. The (0001) growth plane of oriented single crystals was confirmed from the back-ref1ection Laue patterns. From the Hall effects by van der Pauw method, the as-grown $CdS_{0.67}Se_{0.33}$ single crystals were found to be n-type semiconductors. The mobility appeared to be decreased by lattice scattering at temperature range from 150K to 293K and by impurity scattering at temperatures ranging from 30K to 150K In order to explore its applicability in photoconductive cells, we measured the ratio of photo-current to dark-current (pc/dc), maximum allowable power dissipation (MAPD), spectral response and response time respectively. The results indicated that for the samples annealed in Cu vapour the photoconductive characteristics are best. We obtained sensitivity of 0.99, the value of pc/de of $1.84{\times}10^{7}$, the MAPD of 323mW and the rise and decay time of 9.3 ms and 9.7 ms, respectively.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.16 no.3
• /
• pp.155-161
• /
• 1996

For the condition monitoring of the journal bearing in rotating machinery, a system for their diagnosis by acoustic emission(AE) was developed. AE has been used to detect abnormal conditions in the bearing system. It was found from the field application study as well as the laboratory experiment using a simulated journal bearing system that AE RMS voltage was the most efficient parameter for the purpose of current study. Based on the above results, algorithms and judgement criteria for the diagnosis system was established. The system is composed of four parts as follows: the sensing part including AE sensor and preamplifier, the signal processing part for RMS-to-DC conversion to measure AE ms voltage, the interface part for transferring RMS voltage data into PC using A/D converter, and the software part including the graphic display of bearing conditions and the diagnosis program.