• Korean Journal of Pharmacognosy
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• v.30 no.2
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• pp.137-144
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• 1999

Torilin was isolated from haxane fraction of Torilis Fructus extract. Torilin produced inhibition of the acetic acid-induced and phenylquinone-induced writhing syndrome at the oral doses of 30 and 90 mg/kg in mice. It also increased the pain threshold at the oral doses of 30, 90 and 270 mg/kg in the tail pressure method and the Randall-Selitto method. However, it did not show a hypothermic action at the oral doses of 30 and 90 mg/kg in mice. The compound exhibited strong anticarrageenan activity at the oral doses of 90 and 270 mg/kg in rats, and had inhibitory effect on the vascular permeability at the oral doses of 30 and 90 mg/kg in mice. It also showed potent inhibition of leucocyte emigration in CMC-pouch at the doses of 3 and 9 mg/rat, sc. The acute toxicity of torilin was very weak: the $LD_{50}$ values were more than 5000 mg/kg, po and 2000 mg/kg, ip in mice. From the above mentioned results, it was suggested that torilin had potent analgesic and anti-inflammatory activities.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.5 no.1
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• pp.43-59
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• 2006

A compact and broadband $4\times1$ array antenna was developed for 3G smart antenna system testbed. The $4\times1$ uniform linear away antenna was designed to operate at 1.885 to 2.2GHz with a total bandwidth of 315MHz. The array elements were based on the novel broadband L-probe fed inverted hybrid E-H (LIEH) shaped microstrip patch, which offers 22% size reduction to the conventional rectangular microstrip patch antenna. For steering the antenna beam, a commercial variable attenuator (KAT1D04SA002), a variable phase shifter (KPH350SC00) with four units each, and the corporate 4-ways Wilkinson power divider which was fabricated in-house were integrated to form the beamforming feed network. The developed antenna has an impedance bandwidth of 17.32% $(VSWR\leq1.5)$, 21.78% $(VSWR\leq2)$ with respect to center frequency 2.02GHz and with an achievable gain of 11.9dBi. The design antenna offer a broadband, compact and mobile solution for a 3G smart antenna testbed to fully characterized the IMT-2000 radio specifications and system performances.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.37 no.2
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• pp.77-84
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• 2000

In this paper, we discuss a symbol clock extraction scheme based on maximizing the band-edge component of the transmitted signal frequency spectrum for applications to 51.84Mbps VDSL system which uses a 16-QAM. The major characteristics of the digital PLL are examined. In addition, we suggest an efficient design method of a sinusoidal look-up table which is used for NCO.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.37 no.2
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• pp.16-28
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• 2000

In this paper, we propose a navigation algorithm for a mobile robot, which is intelligently searching the goal location in unknown dynamic environments using an ultrasonic sensor. Instead of using "sensor fusion"method which generates the trajectory of a robot based upon the environment model and sensory data, "command fusion"method is used to govern the robot motions. The major factors for robot navigation are represented as a cost function. Using the data of the robot states and the environment, the weight value of each factor is determined for an optimal trajectory in dynamic environments. For the evaluation of the proposed algorithm, we peformed simulations in PC as well as real experiments with ZIRO. The results show that the proposed algorithm is apt to identify obstacles in unknown environments to guide the robot to the goal location safely.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.37 no.6
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• pp.15-24
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• 2000

This paper presents an output feedback robust H$\infty$ control problem for a class of uncertain nonlinear systems, which can be represented by an fuzzy dynamic model. The nonlinear system is represented by Takagi-Sugeno fuzzy model, and the control design is carried out on the basis of the fuzzy model. Using a single quadratic Lyapunov function, the globally exponential stability and disturance attenuation of the closed-loop fuzzy control system are discussed. Sufficient conditions for the existence of robust H$\infty$ controllers are given in terms of linear matrix inequalities(LMIs). Constructive algorithm for design of robust H$\infty$ controller is also developed. The resulting controller is nonlinear and automatically tuned based on fuzzy operation.

• Progress in Superconductivity and Cryogenics
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• v.2 no.1
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• pp.19-23
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• 2000

We are developing a small-sized superconducting magnetic energy storge ($\mu$SMES) magnet with the storage capacity of a few megajoules, which provides electric power with high quality to sensitive electric loads. A kA class superconductor with a high coppe $r^erconductor ratio was selected as a candidate conductor. The superconductor was tested in two points of view, which are basic and important in development of the $\mu$SMES magnet. First, stabilities of the superconductor against localized disturbances such as wire motions were estimated by using a wire heater. Second, the quench current characteristics for different charge rates were also tested. The stability data showed that the short heat pulses made the conductor more unstable. The superconductor had relatively high recovery currents ranging between 40% and 50% of its critical currents. The quench tests indicated that the quench currents of the conductor were independent of current ramp rates up to 3000 A/s and nearly equal to its cuitical current data.ta.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.37 no.2
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• pp.60-68
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• 2000

This paper describes a design methodology for the CMOS current source which can be implemented in standard memory process. The proposed techniques provide a good characteristic against the power-supply variation by utilizing a self-bias circuit and the reduction of the first-order component of the temperature variation through the new temperature compensation technique and include a new current-sensing start-up circuit enabling a robust operation against the voltage noise generated during the operation of the chip. In addition to the circuit-design technology, techniques where the proposed CMOS current-reference circuit can be applied to the clocking circuits of a very high-speed DRAM are presented. The feasibility of the suggested design methodology for the CMOS current reference is demonstrated by both the analytical method and the circuit simulation.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.37 no.2
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• pp.69-76
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• 2000

A dual-modulus prescaler divides the input signal by one of the moduli according to the control signal. In this paper, a new fast dual-modulus prescaler is proposed. The proposed prescaler has a ratioed-NOR structure different from a conventional ratioed-NAND structure. The proposed one can operate at a higher speed by using parallely connected NMOSs instead of using series-connected ones. HSPICE simulation results using HYUNDAI 0.65(m 2-poly 2-metal CMOS process parameters show that the maximum operating frequency of the proposed dual-modulus prescaler is 2.8㎓ with power consumption of 40.7㎽ at 5V supply voltage at $25^{\circ}C$. The proposed dual-modulus prescaler can be utilized for the frequency-synthesis in cellular radio front-ends.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.37 no.2
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• pp.85-95
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• 2000

This paper describes a sensorless control scheme for brushless dc motors(BLDCMs) using a phase shifter(FIPS) which can shift the zero-crossing point of the input signal with a specified amount of phase. The detection performance of the proposed FIPS is independent of the frequency of the input signal and quite robust with respect to the measurement noise. It is shown that the proposed sensorless control scheme using the FIPS is more effective in the respects of noise-robustness and cost than the previously known schemes. The generality and practicality of the proposed sensorless control scheme is demonstrated through performance analysis and experiments under various operating conditions.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.7 no.1
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• pp.41-58
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• 2007

A compact and broadband $4{\times}1$ array antenna was developed for 3G smart antenna system testbed. The $4{\times}1$ uniform linear array antenna was designed to operate at 1.885 to 2.2GHz with a total bandwidth of 315MHz. The array elements were based on the novel broadband L-probe fed inverted hybrid E-H (LIEH) shaped microstrip patch, which offers 22% size reduction to the conventional rectangular microstrip patch antenna. For steering the antenna beam, a commercial variable attenuator (KAT1D04SA002), a variable phase shifter (KPH350SC00) with four units each, and the corporate 4-ways Wilkinson power divider which was fabricated in-house were integrated to form the beamforming feed network. The developed antenna has an impedance bandwidth of 17.32% ($VSWR{\leq}1.5$), 21.78% ($VSWR{\leq}2$) with respect to center frequency 2.02GHz and with an achievable gain of 11.9dBi. The design antenna offer a broadband, compact and mobile solution for a 3G smart antenna testbed to fully characterized the IMT-2000 radio specifications and system performances.