• Toxicological Research
• /
• v.11 no.2
• /
• pp.175-180
• /
• 1995

We found that bufalln, one of the prominent components of the bufadlenolides in the Chinese medicine chan'su, has the potent inhibitory effects on growth and proliferation of the cultured bovine aortlc endothelial (BAE) and human umbilical vein endothelial (HUVE) cells. All naturally-occuring bufadienolides used in this study inhibited the cell growth in a dose-dependent manner. Particularly, bufalin among the bufadienolides showed the strongest inhibitory activity for the cell growth. The order of growth inhibition by bufadienolides on BAE cells was as follows: bufalin > gamabufotalln > bufotalln > cinobufagin > cinobufotalin > resibufogenin. The $IC_50$ values (50% inhibition of cell growth) of bufalin as determined by XTT assay were the range of 1-10 nM in BAE and HUVE cells. Bufalin exhibited a higher sensitivity towards cultured bovine aortic endothelial cells than human umbilical vein endothelial cells.

• Natural Product Sciences
• /
• v.18 no.1
• /
• pp.22-25
• /
• 2012

Five triterpenoids, epifriedelanol (1), friedelin (2), lupeol (3), ${\beta}$-sitosterol (4), daucosterol (5), and one phenyl propanoids ester, trans-docosanoyl ferulate (6) were isolated from the whole parts of Portulaca oleracea. They were determined using a combination of spectroscopic analyses ($^1H-$, $^{13}C$-NMR, and MS data) and evaluated for their cyclooxygenase inhibitory activity. Compound 6 exhibited inhibitory effect with $IC_{50}$ values of $40.2{\mu}M$ and 1.6 mM on COX-1 and COX-2 activities, respectively.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.32A no.9
• /
• pp.98-105
• /
• 1995

Recent microwave IC's reach to the extent of high operating frequencies at which bonding wires limit their performance as dominant parasitic components. Double bonding wires separated by an internal angle have been firstly characterized using the Method of Moments with the incorporation of the ohmic resistance calculated by the phenomenological loss equivalence method. For a 30$^{\circ}$ internal angle, the calculated total reactance is 45% less than that of a single bonding wire due to the negative mutual coupling effect. The radiation effect has been observed decreasing the mutual inductance, whereas for parallel bonding wires it greatly increases the mutual inductance. This calculation results can be widely used for designing and packaging of high frequency and high density MMIC's and OEIC's.

• Journal of the Korean Institute of Telematics and Electronics C
• /
• v.35C no.7
• /
• pp.20-29
• /
• 1998

As the packing density of ICs in recent submicron IC design increases, interconnects gain importance. Because interconnects directly affect on two major components of circuit performance, power dissipation and operating speed, circuit engineers are concerned with the optimal design of interconnects and the aid tool to design them. When circuit models of interconnects are given (including geometry and material information), the analysis process for the given structure is not an easy task, but conversely, it is much more difficult to design an interconnect structure with given circuit characteristics. This paper focuses on the latter process that has not been foucsed on much till now due to the complexity of the problem, and prsents a design aid tool(DATOIS) to synthesize interconnects. this tool stroes the circuit performance parameters for normalized interconnect geometries, and has two oeprational modes:analysis mode and synthesis mode. In the analysis mode, circuit performance parameters are obtained by searching the internal database for a given geometry and interpolates results if necessary . In thesynthesis mode, when a given circuit performance parameter satisfies a set of geometry condition in the database, those geometry structures are printed out.

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

• Transactions on Electrical and Electronic Materials
• /
• v.11 no.4
• /
• pp.178-181
• /
• 2010

An automotive IC voltage regulator which consists of one-chip based on a metal-oxide semiconductor field effect transistor (MOSFET) is investigated experimentally with three types of packaging. The closed type is filled with thermal silicone gel and covered with a plastic lid on the MOSFET. The half-closed type is covered with a plastic case but without thermal silicone gel on the MOSFET. Opened type is no lid without thermal silicone gel. In order to simulate the high temperature condition in engine bay, the operating circuit of the MOSFET is constructed and the surrounding temperature is maintained at $100^{\circ}C$. In the overshoot the maximum was mainly found at the half-closed packaging and the magnitude is dependent on the packaging type and the surrounding temperature. Also the impressed current decreased exponentially during the MOSFET operation.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.14 no.6
• /
• pp.37-44
• /
• 2005

This paper presents fabrication techniques of the optical fiber position sensor (or spindle state monitoring. These include selection of components such as optical fibers, a laser-diode, a photo-diode, and op-amp IC of the signal process circuit. We also describe electric runout problem. The fabricated sensor has a linearity of $1.7\%$ FSO in the air gap range $0.1\~0.6mm$, a resolution of $0.37{\mu}m$ and a bandwidth of 6.3kHz. Finally, we have successfully operated a magnetic bearing spindle system using the sensors.

• Journal of Fisheries and Marine Sciences Education
• /
• v.27 no.3
• /
• pp.833-840
• /
• 2015

This study tries to suggest de-stressing methods for Korean maritime pilots by exploring the components of Job Stress, and investigating relationship between Job Stress and Job Satisfaction. The factor analysis to find out factors influencing Job Stress and multi-variate regression analysis to reveal the relationship between Job Stress and Job Satisfaction were used, and the sample collected by questionnaire survey consisted of 81 Korean maritime pilots. Finally, analysis results of this study provide that 1) peer-relation conflict(IC), Emotional Labour(EL), Responsibility of Decision Making and psychological job demand as variables of maritime pilots' Job Stress are represented, and 2) peer-relation conflict and Responsibility of Decision Making are negatively related with Job Satisfactions.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.15 no.3
• /
• pp.390-396
• /
• 2015

This paper proposes a method to reduce flicker when running an AC-power direct-drive type multiple string LED driver IC. The proposed method greatly decreases flicker using one capacitor and P-type MOSFET transistor (PMOS). The flicker index (FI) was reduced by over 40% through experiments, and less than half of the conventional external components are used in the passive valley fill circuit, which gives an advantage in the cost and utilization in the design of LED lighting modules. The 0.35 um 700 V BCD process was used to manufacture this LED driver.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.58 no.10
• /
• pp.2052-2058
• /
• 2009

The standardized and open information model called common language and information exchange format should be firstly defined for the interoperable power system and two-way information exchange among the components of the power system. The information models and information exchange formats for power facilities and power system applications are being defined in power system area, but the information model and information exchange format for the consumer area are not being yet defined besides of metering information model. An architecture and open standard for the information exchange between energy service provider and consumer are required to provide various value added services through the networking with devices in consumer premise. In this paper, an architecture for the two-way communications between energy service provider and consumer is defined and psXML(power system XML) for the information exchange is designed.