• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.1
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• pp.92-97
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• 2007

This paper performed the basic study for developing the Photodynamic Therapy Equipment for medical treatment. We developed the equipment palpating cell proliferation using a high brightness LED. This equipment was fabricated using a micro-controller and a high brightness LED, and designed to enable us to control light irradiation time, intensity, frequency and so on. Especially, to control the light irradiation frequency, FPGA was used, and to control the change of output value, TLC5941 was used. Control stage is divided into 30 levels by program. Consequently, the current value could be controlled by the change of level in Continue Wave(CW) and Pulse Width Modulation(PWM), and the output of a high brightness LED could be controlled stage by stage. And then, each experiment was performed to irradiation group and non-irradiation group for both Rat bone marrow and Rat tissue cells. MTT assay method was chosen to verify the cell increase of two groups and the effect of irradiation on cell proliferation was examined by measuring 590 nm transmittance of ELISA reader. As a result, the cell increase of Rat bone marrow and tissue cells was verified in irradiation group as compared to non-irradiation group. The fact that specific wavelength irradiation has an effect on cell vitality and proliferation is known through this study.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.11
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• pp.765-770
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• 2001

Metal-ferroelectric-insulator- semiconductor(MFTS) devices by using rapid thermal annealed (RTA) LiNbO$_3$/AIN/Si(100) structures were successfully fabricated and demonstrated nonvolatile memory operations. Metal-insulator-semiconductor(MIS) C-V properties with high dielectric AIN thin films showed no hysteresis and good interface properties. The dielectric constant of the AIN film calculated from the capacitance at the accumulation region in the capacitance-voltage(C-V) characteristics was about 8. The C-V characteristics of MFIS capacitor showed a hysteresis loop due to the ferroelectric nature of the LiNbO$_3$ thin films. Typical dielectric constant value of LiNbO$_3$ film of MFIS device was about 23. The memory window width was about 1.2 V at the gate voltage of $\pm$5 V ranges. Typical gate leakage current density of the MFIS structure was the order of 10$^{-9}$ A/$\textrm{cm}^2$ at the range of within $\pm$500 kV/cm. The ferroelectric capacitors showed no polarization degradation up to about 10$^{11}$ switching cycles when subjected to symmetric bipolar voltage pulse(peak-to-peak 8 V, 50 % duty cycle) in the 500 kHz.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.15 no.6
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• pp.65-72
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• 2001

This paper deals with a novel full digital control of the single-phase PWM(Pulse Width Modulation) inviter for UPS(Uninterruptible Power Supp1y). The voltage and current of output filter capacitor as a state variable are the feedback control input. In the proposed scheme a double deadbeat control consisting of minor current control loop and major voltage control loop have been developed In addition, a second order deadbeat currents control which should be exactly equal to its reference in two sampling time without error and overshoot is proposed to remove the influence of the calculation time delay. The load current prediction is achieved to compensate the load disturbance. The simulation and experimental result shows that the proposed system offers an output voltage with THD(Total Harmonic Distortion) less than 5% at a full nonlinear load.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.8
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• pp.784-790
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• 2009

A forward-looking automotive radar typically utilizes the frequency modulated continuous wave(FMCW) or pulsed-Doppler waveform for the Information acquisition of the target range and velocity. In order to obtain the high resolution target information, however, a narrow pulse width and wide bandwidth are inherently required, thus resulting in high peak power and high speed digital converter processing. In this paper, a stepped-frequency pulsed-Doppler(SFPD) waveform algorithm is proposed for high resolution forward looking automotive radar application. The performance of the proposed SFPD waveform technique is analyzed and compared with the conventional FMCW and PD method. Since this technique can be used for the high resolution target imaging with arbitrary range and Doppler resolution, it is expected to be useful In automotive radar target classification for the precision collision avoidance applications in the future.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.8
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• pp.798-804
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• 2013

In this paper, conducted emission from the LDC(Low-Side DC/DC Converter) of a HEV/EV was analyzed using high-frequency circuit modeling in system-level approach. The conducted emission by PWM process(100 kHz; Switching Frequency) can cause RFI(Radio-Frequency Interference) problems in the AM/FM frequency range. In order to mitigate this conducted emission, a high-frequency equivalent circuit model is proposed by analyzing the fundamental circuits, parasitic components in their parts and connections and non-linear characteristics of MOSFETs, high-power capacitors, inverters, motors, high-power cables, and bus bars which are composed of the LDC. Using these circuit models, results of both simulation and measurement were compared and similarities between them were verified. We are looking forward that this approach can be effectively used in the EMC design of HEV/EV.

• IEIE Transactions on Smart Processing and Computing
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• v.4 no.5
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• pp.354-365
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• 2015

This work presents an Internet of Things (IoT) system for home energy management based on a custom-designed Impulse Radio Ultra-Wideband (IR-UWB) transceiver that targets a generic and multi-standard control system. This control system enables the interoperability of heterogeneous devices: it integrates various sensor nodes based on ZigBee, EnOcean and UWB in the same middleware by utilizing an ad-hoc layer as an interface between the hardware and software. The paper presents as a first the design of the IR-UWB transceiver for a portable sensor node integrated with the middleware layer, and also describes the receiver connected to the control system. The custom-designed low-power transmitter on the sensor node is fabricated with 130 nm CMOS technology. It generates a signal with a 1.1 ns pulse width while consuming $39{\mu}W$ at 1 Mbps. The UWB sensor node with a temperature measurement capability consumes 5.31 mW, which is lower than the power level of state-of-the-art solutions for smart-home applications. The UWB hardware and software layers necessary to interface with the control system are verified in over-the-air measurements in an actual office environment. With the implementation of the presented sensor node and its integration in the energy management system, we demonstrate achievement of the broad flexibility demanded for IoT.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.1
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• pp.1-12
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• 1992

Generally, laser machines with high generated power can be developed by means of enhancing their mean power, since the enhancement of mean power exerts an influence on peripheral parameters and machining performance. In this research, we evaluate the various machining properties by the use of two machines which bear different mean power each other, so that we may study various effects of the enhancement of mean power. As a result, when the mean power comes to be enhanced to 75%, we obtain the increase of output energy up to 69% and of peak power more than 95%, and also obtain almost twice of the cutting speed. Moreover we find the fact that if the test pieces have enough thickness in contrast with output energy, the pulse frequency moves toward the frequency bandwidth which takes proportion to the cutting speed mas well as to the amount of material removal per unit time. In addition it is finally obtained that the laser machine with high output power yields small taper degrees at kerf parts, while it has large cutting widiths and dross lengths.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.37 no.1
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• pp.57-65
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• 2001

The speed control without a speed sensor is expected strongly to progress reliability, simplicity and cost performance of Induction Motor(I.M) systems. Also, it contributes to expansion of I.M systems into various industrial application fields. This paper investigates a novel speed sensorless control method of I.M considering the secondary resistance identification based on the transientless torque control technique. Especially, this paper aimed at the identification of the secondary resistance simultaneously with speed estimation superposing of sinusoidal flux wave to a constant flux value. Furthermore, the secondary flux with some frequency is controlled independently on torque control. The proposed speed estimation method is derived from a motor circuit equation theoretically and also it can be conducted easily by detecting primary motor currents and primary voltage commands at every sampling time. Some numerical simulations with the assumption of using a pulse width modulation(PWM) voltage source inverter are performed to verify the proposed method.

• Journal of the Korean Society of Physical Medicine
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• v.9 no.4
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• pp.415-424
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• 2014

PURPOSE: This study examined the effect of high-frequency transcutaneous electrical nerve stimulation (TENS) and San-Yin-Jiao (SP6) acupressure on primary dysmenorrhea. Furthermore, the difference in effectiveness between the two methods were compared. METHODS: Twenty-six students participated in this study, and were randomly assigned to a high-frequency TENS group(experimental 1, n=9), a San-Yin-Jiao (SP6) acupressure group(experimental 2, n=9), and no treatment group(control, n=8). They were assessed and treated on the first day of their menstruation. The TENS protocol included applying 20 minutes of stimulation with a frequency of 100Hz, $100{\mu}sec$ pulse width. Four electrodes were placed on the skin 3 cm from midline at T12-L1 and S2-3 paravertebral muscles. San-Yin-Jiao (SP6) acupressure should be applied with the thumb for 10 minutes(8 seconds pressure and 2 seconds rest) on the SP6 acupoint. This procedure should be repeated for the other foot. Dysmenorrheal pain measured two pain assessment tools (VAS, DPT) pre-treatment; immediate post-treatment; 30minutes, 1, 2hours; and 3, 4, 5, 6, 24 hours after the VAS test were added. RESULTS: The results showed significant differences in pain assessments (VAS, DPT) after treatment for subjects of experimental group1 (p<.05) and experimental group2 (p<.05), whereas the between-group comparison found no statistically significant differences. CONCLUSION: This result supports the idea that using two methods could be effective in pain reduction among students who suffered from primary dysmenorrhea.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.5
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• pp.416-425
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• 2002

In this Paper, It is analysed 5 GHz frequency characteristics that carry out interference experimental under the indoor environments for understanding propagation interference between existing 5 GHz band wireless communication system and 5 GHz band wireless LAN system. The interference signal which was generated by signal generator injected to 5 GHz Wireless LAN communication system measured interference characteristics and This radio propagation main interference factors were classified received power level separation by interference source frequency and interference source frequency pulse period & width separation. It is measured transmission rate according to variable data and packet size for conforming the quality of 5 GHz band wireless LAN system. We measured the packet data loss rate and power level of received signal and analyzed its frequency characteristics effected by interference signal.