• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.28-32
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• 2003

Aperture has been employed on the ground plane in the Hair Pin resonator. Aperture made by etching the part of the ground effected coupling coefficient and then quality factor of Hair Pin resonator has been increased. When the hair pin oscillator using aperture has been compared with the conventional hair pin oscillator using microstrip, it has been improved the phase noise about 19dBc @100KHz. Oscillation frequency of the hair pin oscillator using aperture has been 5.83GHz band and output power is -4.33dBm.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.4
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• pp.1655-1659
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• 2016

Celecoxib, a selective inhibitor of COX-2, showed cytotoxic effects in many cancer cell lines including cervical cancer cells. This study investigated the effect of celecoxib on cell cycle arrest in HeLa cervical cancer cells through p53 expression. In vitro anticancer activity was determined with the 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) method. A double staining method was applied to investigate the mechanism of cell death, cell cycling was analyzed by flow cytometryand immunocytochemistry was employed to stain p53 expression in cells. Celecoxib showed strong cytotoxic effects and induced apoptosis with an $IC_{50}$ value of $40{\mu}M$. It induced cell cycle arrest at G2/M phase by increasing level of p53 expression on HeLa cells.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.31-34
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• 1998

In this paper, a Single-phase Active Rectifier(SAR) with high power factor capability for inverter air-conditioner is adopted for satisfying the international standards of input current harmonics, IEC 1000-3-2. Comparing the conventional boost power factor correction circuit, one diode drop is reduced in the power flow path of the SAR circuit, so the system efficiency is improved. To apply the control IC, such as UC3854, ML4821 and so forth, to the SAR, the adequate sensing circuits are proposed. The design rules of passive components and two control loops are also presented. The prototype SAR circuit with 3㎾ power consumption is builted and tested to verify the operation of the proposed circuit.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.677-682
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• 1998

A Single-phase Active Rectifier (SAR) [4-6] with high power factor capability is adopted to satisfy the international harmonic current standards such as IEC 1000-3-2. To minimize the input current distortion and to apply the control IC, such as FA5331, UC3854, ML4821 and so forth, the new adequate sensing circuits of the input voltage and current are proposed. There are tow methods applicable the SAR to inverter air-conditioner from the viewpoint of both efficiency and cost. The selecting methods of the passive components are presented for the two approaches. Using the determined components, the loss analyses are carried out. The prototype SAR circuits of these two approaches with 3kW power consumption are built and the operation and performance of the circuits with power factor correction capability are verified through the experimental results.

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.1984-1987
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• 2002

This paper describes the design and implementation of a single-chip digitally synthesized 0-35MHz agile function generator. The chip comprises an integrated direct digital synthesizer (DDS) with a 10-bit on- chip digital-to-analog converter (DAC) using an n-well single-poly triple-metal 0.5-$\mu\textrm{m}$ CMOS technology. The main features of the chip include maximum clock frequency of 100 MHz at 3.3-V supply voltage, 32-bit frequency tuning word resolution, 12-bit phase tuning word resolution, and an on-chip 10-bit DAC. The chip provides sinusoidal, ramp, saw-tooth, and random waveforms with phase and frequency modulation, and power-down function. At 100-MHz clock frequency, the chip covers a bandwidth from dc to 35 MHz in 0.0233-Hz frequency steps with 190-ns frequency switching speed. The complete chip occupies 12-mm$^2$die area and dissipates 0.4 W at 100-MHz clock frequency.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.533-534
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• 2008

This paper presents a multi-phase ring VCO for low-cost, low-power GPS receiver. In the RF band used in GPS, L1 band is now in commercial-use and L2,L5 are predicting to be commercial-use soon. Thus Wide band PLL and Cost-effective IC solutions are required for future multi-band GPS receiver that received three types band at once. A new PLL architecture for multi-band GPS application is proposed. Ring VCO is even smaller than LC-VCO and a good alternative for low-cost solution. Proposed multi-phase ring VCO offers wide frequency range covering L1, L2, and L5 band, 20% reduction of area, 23% reduction of PLL power and can generate I/Q without extra I/Q generator.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1143-1145
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• 2000

In this paper, it presents the design and implementation of a Microstep control IC using Programmable Logic Device(PLD). A Microstep driver is implemented with a 5-phase hybrid stepping motor, which has a Pentagon winding, power MOSFETs, and some devices to improve the system characteristics. The Microstep driving method is used for high performance motion control, low vibration and low noise in motor control system. The improvement of the electrical and mechanical driving characteristic of a step motor is achieved by applying microstep driver.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.910-915
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• 2003

This paper describes the design of a 2-phase stepping motor driver using CPLD(Complex Programmable Logic Device). The driver IC such as L297 (SGS-Thomson Microelectronics), which is mostly used has some problems in PWM control because of the switching noise of power MOSFETs. It causes current ripple and acoustic noise. To improve theses characteristics, we proposed a new current control method that the output PWM frequency is almost constant using a digital filter. Also we proposed constant current method for 1-2 phase(half step) excitation. The proposed method is implemented with CPLD(Xilinx, XC9572-PC44). Experimental results show the effectiveness of the proposed method.

• Proceedings of the PSK Conference
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• 2003.10b
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• pp.183.3-183.3
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• 2003

Phenanthroindolizidine alkaloid, (-)-antofine has attracted attention because of its extremely potent inhibition of cancer cell growth (Its $IC_50$ values have the low nanomolar range). The frist asymmetric total synthesis of (-)-antofine is described. An important feature of this synthesis is the creation of a stereogenic center by enantioselective alkylation using the phase transfer catalyst (PTC) and ring-closing metathesis (RCM) for pyrrolidine ring construction. This synthesis is efficient to allow the asymmetric preparation of other naturally occurring phenanthroindolizidine and phenanthroquinolizidine alkaloid.

• Journal of the Korean Society of Food Science and Nutrition
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• v.29 no.4
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• pp.719-725
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• 2000

This study focused on the purification and characterization of ACE inhibitor from Porphyra yezoensis. The dried Porphyra yezoensis was ground and hydrolyzed with 2.5 N HCl, followed by neutralization and centrifugation. Then, the subsequential purification of ACE inhibitor was carried out by Amberlite XAD 8, DEAE-Toyopearl 650C, Sephadex LH-20 column chromatography and reverse phase HPLC with C18 column. The purified ACE inhibitor was peptide which consisted of glycine (24.5%), arginine (56.8%) and proline (18.8%). Also, it showed the competitive inhibition pattern to ACE. The apparent molecular mass of purified peptide was 580 dalton, and an IC50 value of ACE inhibitor was 10.6 $\mu\textrm{g}$.