• Journal of IKEEE
• /
• v.22 no.2
• /
• pp.495-498
• /
• 2018

In this paper, we propose an DAP system for dose evaluation of medical and industrial X-ray generator. Based on the DAP measurement technique using the Ion-Chamber, the proposed system can clearly measure the exposure radiation dose generated by the diagnostic X-ray apparatus. The hardware part of the DAP measures the amount of charge in the air that is captured by an X-ray. The high-speed processing algorithm part for cumulative radiation dose measurement through microcurrent measures the amount of charge captured by X-ray at a low implementation cost (power) with no input loss. The wired/wireless transmission/reception protocol part synchronized with the operation of the X-ray generator improves communication speed. The PC-based control program part for interlocking and aging measures the amount of X-ray generated in real time and enables measurement graphs and numerical value monitoring through PC GUI. As a result of evaluating the performance of the proposed system in an accredited testing laboratory, the measured values using DAP increased linearly in each energy band (30, 60, 100, 150 kV). In addition, since the standard deviation of the measured value at the point of 4 division was ${\pm}1.25%$, it was confirmed that the DAP showed uniform measurements regardless of location. It was confirmed that the normal operation was not less than ${\pm}4.2%$ of the international standard.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 1999.05a
• /
• pp.330-334
• /
• 1999

This paper presents a new transient voltage blocking device (TBD) for commucation facilities with low power and high frequency bandwidth. Conventional protection devices have some problems such as low frequency bandwidth, low energy capacity and high remnant voltage. In order to improve these limitations, the new TBD, which consists of a gas tube, avalanche diodes and junction type field effect transistors (JFETs), was designed and fabricated JFETs were used as an active non-linear element and a high speed switching diode with low capacitance limits high current. Therefore the avalanche diodes with low energy capacity are protected from the high current, and the TBD has a very small input capacitance. From the performance test using surge generator, which can produce 1.2/50${\mu}\textrm{s}$ 4.2 k$V_{max}$, 8/20${\mu}\textrm{s}$ 2.1 kA$\sub$max/, it is confirmed that the proposed TBD has an excellent protection performance in tight clamping voltage and limiting current characteristics.

• Journal of ILASS-Korea
• /
• v.5 no.3
• /
• pp.37-44
• /
• 2000

High velocity, gas-assisted liquid drop trajectories were investigated under well-controlled experimental conditions at elevated gas densities and room temperature. A monodisperse stream of drops which are generated by a vibrating-orifice drop generator were injected into a transverse high velocity gas stream. The gas density and air jet velocity were adjusted independently to keep the Weber numbers constant. The Weber numbers studied were 72, 148, 270, 532. The range of experimental conditions included studied the three drop breakup regimes previously referred as bag, stretching/thinning and catastrophic breakup regimes. High-magnification photography and conventional spray field photographs were taken to study the microscopic breakup mechanisms and the drop trajectories in high velocity gas flow fields, respectively. The parent drop trajectories were affected by the gas density and the gas jet velocities and do not show similarity with respect to the either Weber or the Reynolds number, as expected.

• Journal of Advanced Marine Engineering and Technology
• /
• v.23 no.2
• /
• pp.159-167
• /
• 1999

This paper presents a new transient voltage blocking device(TOBD)which low power and high frequency bandwidth to protect info-communication facilities from transient voltages. Conventional protection devices have some problems such as low frequency bandwidth low ener-gy capacity and high remnant voltage. in order to improve these limitations a hybrid type TOBD which consists of a gas tube avalanche diodes and junction type field effect transistor (JFETs) is developed. The TOBD differs from the conventional protection devices in configuration and JFETs are used as an active non-linear element and a high speed switching diode with low capacitance limited high current. Therefore the avalanche diode with low energy capacity are protected from the high current and the TOBD has a very small input capacitance. From the performance test using combination surge generator which can produce $1.2/50{\mu}m$ 4.2 kV/max, $8/20{\mu}m$ 2.1 kAmax it is confirmed that the proposed TOBD has an excellent protection per-formance in tight clamping voltage and limiting current characteristics.

• 한국전산유체공학회:학술대회논문집
• /
• 2011.05a
• /
• pp.236-239
• /
• 2011

This paper introduces the design concepts and characteristics of WinDS3000$^{TM}$(TC IIa) which is a trade name of Doosan's 3MW offshore/onshore wind turbine. WinDS3000$^{TM}$(TC IIa) has been designed in consideration of high Reliability, Availability, Maintainability and Serviceability (RAMS) and low cost of electricity (CDE) for the TC IIa condition based on GL guideline. An integrated drive-train design with an innovative three-stage gearbox has been introduced to minimize nacelle weight of the wind turbine and to enhance a high reliability for transmission. A permanent magnet generator with full converter system has been introduced to get higher efficiency in partial load operation and grid-friendly system for both 50 Hz and 60 Hz. A pitch-regulated variable speed control system has been introduced to control wind turbine power while generator reaction torque can be adjusted almost instantaneously by the associated power electronics. The wind turbine has been also equipped with condition monitoring and diagnostic systems in order to meet maintainability requirements.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.49 no.7
• /
• pp.359-364
• /
• 2000

This paper is introducing a newly developed spark-gap switch with dual trigger system, into which the current from the voltage source is injected along with the test sequence during the synthetic testing of high voltage circuit-breaker. The currently-used spark gap switch is narrow in operating range due to the use of the method of triggering energy being injected by single way. As a result, the frequent happening of misoperation has greatly reduced the test quality and test efficiency and has required the cost of maintenance excessively. In this study, accordingly, in order to basically remove these problems, another triggering system is installed to the opposite direction on the existing triggering system; attaching the same time and the same rising time of pulse wave as on the existing system, so that at a comparatively trigger gap distance from the main electrode(the gap can be operated at 60% of self-break voltage, while at 80% in the current system), the main electrode has been enabled to be closed by the development of spark gap switch with dual trigger system.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.56 no.8
• /
• pp.1445-1449
• /
• 2007

This paper presents the DOD (Drop-On-Demand) characteristic using the electrostatic field induced inkjet printing system. In order to achieve the DOD characteristic of electrostatic field induced inkjet printing, applied the bias voltage of 1.4 kV and the pulse voltage of $2.0\;kV\;{\sim}\;2.7\;kV$ using high voltage pulse generator. Electrostatic field induced droplet ejection is directly observed using a high-speed camera and for investigated DOD characteristic, CNT ink used. The electrostatic field induced inkjet head system has DOD characteristic using pulse generator which can be applied pulse voltage. The bias voltage has a good condition which form meniscus and has micro dripping mode for small size micro droplet. Also, the droplet size decreases with increasing the applied pulse voltage. This paper shows DOD characteristic at electrostatic field induced inkjet head system, Therefore. electrostatic DOD inkjet head system will be applied industrial area comparing conventional electrostatic inkjet head system.

• Journal of Advanced Marine Engineering and Technology
• /
• v.38 no.3
• /
• pp.262-268
• /
• 2014

This research introduces the structural design and the validation results of the flexible high speed coupling for 2MW class wind turbine which transmit and cut off torque between gear box and generator. The high speed coupling requires electrical insulation to prevent electrical surface damages on gear box. Therefore glass fiber reinforced plastics is applied to absorb the vibration and deformation of power train and to transmit required torque. Finite element analysis was performed to optimize the thickness and accumulation number of glass fiber reinforced plastics. Torque limiter which cut off the abnormal torque is designed in frictional disc type. The design of the coupling was validated with the performance test of prototype.

• The Transactions of the Korea Information Processing Society
• /
• v.7 no.1
• /
• pp.235-244
• /
• 2000

This paper presents a low power PLL based clock geneator circuit for microprocessors. It generates 32MHz${\sim}$1GHz clocks and can be integrated inside microprocessor chips. A high speed D Flip-Flop is designed using dynamic differential latch and a new Phase Frequency Detector(PFD) based on this FF is presented. The PFD enjoys low error characteristics in phase sensitivity and the PLL using this PFD has a low phase error. To improve the linearity of voltage controlled oscillator(VCO) in PLL, the voltage to current converter and current controlled oscillator combination is suggested. The resulting PLL provides wide lock range and extends frequency of generated clocks over 1 GHz. The clock generator is designed by using $0.65\;{\mu}m$ CMOS full custom technology and operates with $11\;{\mu}s$ lock-in time. The power consumption is less than 20mW.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.8 no.1
• /
• pp.170-178
• /
• 2004

In this work a high speed 8-error correcting Reed-Solomon decoder is designed using the modified Euclid algorithm. Decoding algorithm of Reed-Solomon codes consists of four steps, those are, compute syndromes, find error-location polynomials, decide error-locations, and determine error values. The decoding speed is increased and the latency is reduced by using the parallel architecture in the syndrome generator and a faster clock speed in the modified Euclid algorithm block. In addition. the error locator polynomial in Chien search block is separated into even and odd terms to increase the overall speed of the decoder. All the functionalities of the decoder are verified first through C++ programs. Verilog is used for hardware description, and then the decoder is synthesized with a $.25{\mu}m$ CMOS TML library. The functionalities of the chip is also verified through test vectors. The clock speed of the chip is 250MHz, and the maximum data rate is 1Gbps.