• Progress in Superconductivity
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• v.13 no.2
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• pp.105-110
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• 2011

SQUID sensor-based ultra low-field magnetic resonance apparatus with ${\mu}T$-level measurement field requires a strong prepolarization magnetic field ($B_p$) to magnetize its sample and obtain magnetic resonance signal with a high signal-to-noise ratio. This $B_p$ needs to be ramped down very quickly so that it does not interfere with signal acquisition which must take place before the sample magnetization relaxes off. A MOSFET switch-based $B_p$ coil driver has current ramp-down time ($t_{rd}$) that increases with $B_p$ current, which makes it unsuitable for driving high-field $B_p$ coil made of superconducting material. An energy cycling-type current driver has been developed for such a coil. This driver contains a storage capacitor inside a switch in IGBT-diode bridge configuration, which can manipulate how the capacitor is connected between the $B_p$ coil and its current source. The implemented circuit with 1.2 kV-tolerant devices was capable of driving 32 A current into a thick copper-wire solenoid $B_p$ coil with a 182 mm inner diameter, 0.23 H inductance, and 5.4 mT/A magnetic field-to-current ratio. The measured trd was 7.6 ms with a 160 ${\mu}F$ storage capacitor. trd was dependent only on the inductance of the coil and the capacitance of the driver capacitor. This driver is scalable to significantly higher current of superconducting $B_p$ coils without the $t_{rd}$ becoming unacceptably long with higher $B_p$ current.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1009-1012
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• 2008

We have succeeded in producing the world $1^{st}$ TFT LCD panel adapting the data line sharing method. In the data line sharing structure, two neighboring pixels share one data line. We also adapted time shared data driving with a-Si TFT based circuit integration technology of LG Display's own. By using these technologies, we can reduce the number of source driver ICs by half, compared to that of the existing gate driver integrated TFT LCD panel.

• Journal of Korea Multimedia Society
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• v.10 no.9
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• pp.1209-1219
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• 2007

It is difficult to run 3D graphics based application on the embedded system with hardware constraints. Therefore, such a system must have a systematic infrastructure which can process various operations with respect to 3D graphics through any graphic acceleration module. In this paper, we present a method to implement 3D graphics acceleration device driver on Tiny X platform which provide an open source graphics windowing environment. The proposed method is to initialize the driver step by step so that the direct rendering infrastructure can use it properly. Moreover, we evaluated overall 3D graphics performance of an implemented driver through a simple but effective benchmark program.

• Journal of Power Electronics
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• v.16 no.4
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• pp.1268-1276
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• 2016

A triode for alternating current (TRIAC) dimming light emitting diode (LED) driver, which adopts a variable switched capacitor for LED dimming and LED power regulation, is proposed in this paper. The proposed LED driver is power efficient, reliable, and long lasting because of the TRIAC switch that serves as its main switch. Similar to previous TRIAC dimmers for lamps, turn-on timing of a TRIAC switch can be controlled by a volume resistor, which modulates the equivalent capacitance of the proposed variable switched capacitor. Thus, LED power regulation against source voltage variation and LED dimming control can be achieved by the proposed LED driver while meeting the global standards for power factor (PF) and total harmonic distortion (THD). The long life and high power efficiency of the proposed LED driver make it appropriate for industrial lighting applications, such as those for streets, factories, parking garages, and emergency stairs. The detailed analysis of the proposed LED driver and its design procedure are presented in this paper. A prototype of 80 W was fabricated and verified by experiments, which showed that the efficiency, PF, and THD at V_s = 220 V are 93.8%, 0.95, and 22.5%, respectively; 65 W of LED dimming control was achieved with the volume resistor, and the LED power variation was well mitigated below 3.75% for 190 V < V_s < 250 V.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.4
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• pp.358-365
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• 2011

Recently, the LED(Light Emitting Diode) replacing incandescent light bulbs and fluorescent light has great attentions as a most promising candidate for the next generation lighting source due to its environment-friendly characteristics, long life and excellent efficiency. Moreover, since it is a semiconductor device which can convert the electric energy to visible light at a very high speed, it can also used as a communication device. Therefore, the VLC(Visible Light Communication) using the LED can perform the near field communication and lighting function at the same time without additional expenses. However, since the switching device of the conventional LED driver for VLC is operated in the linear region, there exist several drawbacks such as a poor power conversion efficiency and serious heat generation. On the other hand, since the proposed driver is operated in the on/off switching region, it features a higher efficiency and more improved heat generation. To verify the validity of the proposed LED driver, experimental results from a prototype of 20W rated LED driver applied to 3MHz bps broadcasting audio system are given.

• Proceedings of the IEEK Conference
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• 2003.11c
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• pp.309-312
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• 2003

In this study, the electrical characteristic of Symmetric high voltage MOSFET (SHVMOSFET) for display driver IC were investigated. Measurement data are taken over range of temperature (300K-400K) and various extended drain length. In high temperature condition(>400K), drain current decreased over 20％, and specific on-resistance increased over 30％ in comparison with room temperature.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.11a
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• pp.229-229
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• 2004

• Proceedings of the KAIS Fall Conference
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• 2001.05a
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• pp.135-138
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• 2001

본 논문에서는 교류 전원인 220V 전원을 간단한 다이오드 및 커패시터만으로 정류한 후 BLDC 모터를 구동할 수 있는 드라이버를 개발하였다. 구동단은 저렴한 전력용 트랜지스터와 FET를 사용함으로써 비용을 줄일 수 있게 하였으며, 실험 결과 잘 동작함을 확인하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.2
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• pp.191-198
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• 2014

As an NMEA 2000 is a standard for communicate to other electronic equipment, it implemented a Universal gateway based on this ship's network. To implement a NMEA 2000 based Universal gateway, it is porting a NMEA 2000 stack source and CAN device driver source to board, and then it connected a board that equip with various communication protocol(CAN, RS232, USB, Ethernet port). To verify converted ship's data to a developed gateway, it connected pc based simulater program and monitoring program to a developed board. so we can see a ship's data through NEMA 2000 network. We verified a gateway performance and analyzed a generated ship's data from simulator program through a monitoring program that was connected a gateway and NMEA 2000 network. so it was designed, implemented to allow monitoring through utilizing a communication method that user wants.

• The Journal of the Acoustical Society of Korea
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• v.33 no.2
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• pp.87-93
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• 2014

If one identifies the detailed distribution of pressure and axial velocity at a source plane, the position and strength of major noise sources can be known, and the propagation characteristics in axial direction can be well understood to be used for the low noise design. Conventional techniques are usually limited in considering the constant source characteristics specified on the whole source surface; then, the source activity cannot be known in detail. In this work, a method to estimate the pressure and velocity field distribution on the source surface with high spatial resolution is studied. The matrix formulation including the evanescent modes is given, and the nearfield measurement method is proposed. Validation experiment is conducted on a wide duct system, at which a part of the source plane is excited by an acoustic driver in the absence of airflow. Increasing the number of evanescent modes, the prediction of pressure spectrum becomes further precise, and it has less than -25 dB error with 26 converged evanescent modes within the Helmholtz number range of interest. By using the converged modal amplitudes, the source parameter distribution is restored, and the position of the driver is clearly identified at kR = 1. By applying the regularization technique to the restored result, the unphysical minor peaks at the source plane can be effectively suppressed with the filtering of the over-estimated pure radial modes.