• Korean Journal of Food Science and Technology
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• v.36 no.3
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• pp.518-521
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• 2004

Ginseng saponin was isolated from panax ginseng root using high-speed countercurrent chromatography (HSCCC). Preliminary studies were performed to optimize physical properties of two-phase solvent system and operating parameters including rotation speed of column, elution mode of mobile phase, and flow rate. Two-phase solvent system for isolation of ginseng saponins was composed of chloroform, water, and methanol as blending solvent. Chloroform-aqueous methanol (4:6) systems with various concentration of methanol in water were evaluated for retention of stationary phase in column. Retention of stationary phase decreased with increasing flow rate in tail-to-head elution mode using upper phase as mobile phase and head-to-tail elution mode using lower phase as mobile phase. Latter mode produced high retention at flow rate of 5 mL/min. Optimum conditions for isolation of saponin were chloroform/methanol/water (40/39/21) solvent system; mobile phase, of lower organic layer, flow rate, of 5 mL/min, head to tail elution mode, rotation speed, of 800 rpm, and sample injection, of $200{\mu}L$, Recovery yield of ginseng saponin from panax ginseng root extract by HSCCC was 63.6%, and the purity of HSCCC fractions was verified by TLC.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.310-311
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• 2008

We have studied electro-optical characteristics of fringe-field switching (FFS) mode with high $d{\Delta}n$ according to the electrode position. In this device, the fringe-electric field drives the LCs to rotate so that the dielectric torque is electrode-positional dependent, which results in electrode-position dependency in the LC's rotating angle. We confirmed polarization microscope image and chromaticity diagram at the different electrode position with LC that have high $d{\Delta}n$. Since the FFS mode is influenced by horizontal and vertical electric field, the FFS mode modulates light using both phase retardation and polarization rotation effect, which had already been verified with previous studies. However, from another point of view, tight modulation of FFS mode has been demonstrated by performing experiment and calculated simulation at the high $d{\Delta}n$ LC cell.

• Journal of IKEEE
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• v.18 no.4
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• pp.586-592
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• 2014

In this paper, high efficiency power management IC(PMIC) with DT-CMOS(Dynamic threshold voltage Complementary MOSFET) switching device is presented. PMIC is controlled PWM control method in order to have high power efficiency at high current level. The DT-CMOS switch with low on-resistance is designed to decrease conduction loss. The control parts in Buck converter, that is, PWM control circuit consist of a saw-tooth generator, a band-gap reference(BGR) circuit, an error amplifier, comparator circuit, compensation circuit, and control block. The saw-tooth generator is made to have 1.2MHz oscillation frequency and full range of output swing from supply voltage(3.3V) to ground. The comparator is designed with two stage OP amplifier. And the error amplifier has 70dB DC gain and $64^{\circ}$ phase margin. DC-DC converter, based on current mode PWM control circuits and low on-resistance switching device, achieved the high efficiency nearly 96% at 100mA output current. And Buck converter is designed along LDO in standby mode which fewer than 1mA for high efficiency. Also, this paper proposes two protection circuit in order to ensure the reliability.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.4 s.107
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• pp.351-357
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• 2006

In this paper, a direct $TM_{01}-TE_{11}$ mode converter of circular waveguide which is used the approximated design method of mode conversion between $TM_{01}$ and $TE_{11}$ modes is designed for radiation with the maximum directivity of high power energy into air (rom high power microwave antenna system. The proposed direct $TM_{01}-TE_{11}$ mode converter is calculated and designed with an approximated method for non-linear function about an extended non-constant serpentine type of circular waveguide. Then, the designed mode converter is optimized by length of 200 mm and efficiency above 95% by FIM simulation and achieved short length and high efficiency of the antenna by results of fabricated and measured characteristics.

• JSTS:Journal of Semiconductor Technology and Science
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• v.4 no.4
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• pp.275-279
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• 2004

A new burst mode clock and data recovery circuit is realized that improves the previousldy-known gated-oscilletor technique with half rate clock recovery, The circuit was fabricated with 0.25um CMOS technology, and its functions were confirmed up to 1 Gbps.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.207-212
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• 2001

The aim of this study is to present a practical and simple method for decision of ultimate failure mode of high-strength concrete beam members, based on interaction between shear strength and displacement ductility. Four tests were conducted on full-scale beam specimens having concrete compressive strength of 410kgf/$cm^{2}$. Prediction of failure mode from presented method and comparison with test results are also presented

• Proceedings of the Membrane Society of Korea Conference
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• 1993.10a
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• pp.13-20
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• 1993

The sorption equilibria and permeation rates for carbon dioxide in such glassy polymer membranes with high glass-transition temperature as polyimide, polyetherimide, polysulfone and polyethersulfone membranes, were measured. The sorption isotherms for these systems can be described well by the dual-mode sorption model, whereas the pressure dependences of the mean permeability coefficients are simulated better by a modified dual-mode mobility model than the conventional dual-mode mobility model in which the Henry's law and Langmuir populations execute four kinds of diffusive movement.

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.397-398
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• 2013

Fairchild Green Mode off line buck switch for low standby power consumption and high reliability is presented. By reducing operating current and optimizing switching frequency, 20mW power consumption is achieved. High performance trans-conductance amplifier and green mode function improve the ripple and regulation in the output voltage. The conventional $FPS^{TM}$ buck and novel Fairchild buck switch are compared to show the improvement of performance. Experimental results are showed using 2W evaluation board.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1998.10a
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• pp.36-43
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• 1998

The purpose of study is to propose numerical assessment methods of lateral deformation shape under lateral loads for regular high-rise buildings. The normalized 1st mode shape is used to assess lateral deformation shape. The assessment method are mass participation factor, representative value by RMS, the mean value, median of the nomalized 1st mode shape. These methods are able to know a fundamental lateral deformation shape of the building and effects of interactive systems numerically. Generally the characteristics of normalized 1st mode shape for various models coincide with numerical assessment results.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.860-863
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• 2003

In this paper high power SMU(Source Measurement Unit) having 50V/1.5A source/measure range has been designed and implemented. The SMU has two operation mode, voltage mode and current mode. The SMU can be used as variable voltage source, variable current source, voltage meter, or current meter. Combining two different unit, output power can be doubled as 100V/1.5A. The developed SMU tan be used many semiconductor testing system and electronic device inspecting system.