• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 전기학술대회논문집
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• pp.1035-1040
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• 2005

This paper deals with the design rule and performance results of the surge protective devices (SPDs) for low-voltage mains on shipboard. The proposed SPDs consists of a metal oxide varistors (MOV) and a L-C filter to improve noise-elimination performance. Three kinds of SPDs are fabricated and tested by using a combination surge generator which produce the standard impulse current of 8/20${\mu}s$ 2.1kA. As a results, the proposed SPDs with series L-C filter have more excellent transient blocking and noise reduction performance than the conventional ones.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2002년도 전력전자학술대회 논문집
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• pp.759-762
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• 2002

A ZCT(Zero Current Transition) PWM(Pulse-Width-Modulation) boost converter using parallel MOSFET switch is proposed in this paper. The IGBT(main switch) of the proposed converter is always turned on with zero current switching and turned off with zero current/zero voltage switching. The MOSFET(auxiliary switch) is also operates with soft switching condition. In addtion to, the proposed converter eliminates the reverse recovery current of the freewheeling diode by adding the resonant inductor, Lr, in series with the main switch. Therefore, the turn on/turn off switching losses of switches are minimized and the conduction losses by using IGBT switch are reduced. In addition to, using parallel MOSFET switch overcomes the switching frequency limitation occurred by current tail. As mentioned above, the characteristics are verified through experimental results.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 가을 학술발표회 논문집
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• pp.253-258
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• 2002

In this study the confining pressure dependancy of internal friction angle of rock materials are discussed based on the results of a series of large triaxial tests under consolidated-drained condition. The rock materials tested are two kinds of grain-size distribution ;one is well graded, the other poorly graded(a uniform distribution). The obtained results shows that the internal friction angle of rock materials decreases more sharply in low stress level than in high stress level, and the test constants A and b in De Mello's failure criterion on rockfill materials are A =0.683∼l.584, b=0.712∼l.015 for the well graded and A=1.145∼l.523, b=0.788∼0.880 for the poorly graded.

• 대한인간공학회지
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• 제16권2호
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• pp.15-27
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• 1997

Brain potential is described using the mesocolumnar activity defined by averaged firings of excitatory and inhibitory neuron of neocortex. Lagrangian is constructed based on SMNI(Statistical Mechanics of Neocortical Interaction) and then Euler Lagrange equation is obtained. Excitatory neuron firing is assumed to be amplitude- modulated dominantly by the sum of two modes of frequency .omega. and 2 .omega. . Time series of this neuron firing is calculated numerically by Euler Lagrangian equation. I .omega. L related to low frequency distribution of power spectrum, I .omega. H hight frequency, and Sd(standard deviation) were introduced for the effective extraction of the dynamic property in the simulated brain potential. The relative behavior of I .omega. L, I .omega. H, and Sd was found by parameters .epsilon. and .gamma. related to nonlinearity and harmonics respectively. Experimental I .omega L, I .omega. H, and Sd were obtained from EEG of human in rest state and of canine in deep sleep state and were compared with theoretical ones.

• 약학회지
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• 제32권2호
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• pp.125-128
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• 1988

Geranylation of some synthetic and natural flavones have yielded cytotoxic products against L1210 coll; 5,2´-dihydroxy-6,7,8-trimethoxy-6´-geranyloxyflavone 4$(8.5{\mu}g/ml)$, 5,6-dihydroxy-7-gerenyloxyflavone 9$(2.3{\mu}g/ml)$. 2 has showed the same range of cytotoxicity as the starting material, 5,2´-dihydroxy-6,7,8-trimethoxy-6´-benzyloxyflavone$(17.0{\mu}g/ml)$. The cytotoxicity of 4 was lower than its starting substance, 5,2´,6´-trihydroxy-6,7,8-trimethoxyflavone $(4.5{\mu}g/ml)$. On geranylating 5,6,7-trihydroxyflavone(baicalein, $15.0{\mu}g/ml$) the cytotoxic activity has been strongly potentiated($2.3{\mu}g/ml$ of 9). The presence of at least a free hydroxy group in B-ring of Skullkapflavone II-type flavones. was essential for a high activity. A larger RD-group than methoxy in the B-ring has weakened the activity. The cytotoxicities of baicalein series could not be correlated to their structures.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 추계학술대회 논문집 학회본부 B
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• pp.271-273
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• 2000

This paper presents the dynamic characteristics Linear DC Motor(LDM) using 3 Dimensional Equivalent Magnetic Circuit Network Method(3-D EMCN) by voltage driven. The movement of mover substitutes for the movement of magnetization in permanent magnet expressed by Fourier series. The Dynamic characteristics are carried out from coupling the electrical circuit equation and mechanical kinetic equation.

• 농촌계획
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• 제9권2호
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• pp.1-6
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• 2003

This study was performed to investigate the degree of pollution of sediments of stream and reservoir in rural area. A series of field investigations were carried out for Kyongki-do area and chemical analysis were performed for sediment samples. It was found that some samples were heavily polluted with phenol and TPH and gave off a malodor. Soil Pollution Scores(SPSs) was determined for sediment samples. Some samples were classified to Soil Pollution Class(SPC) 2 and 3. For recycling and disposal of dredged sediments from stream and reservoirs, these polluted sediments should be carefully considered. In the environmental improvement operations of rural area, the degree of pollution of sediments of stream and reservoir are carefully investigated and suitable counterplan must be established.

• Journal of information and communication convergence engineering
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• 제19권4호
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• pp.263-268
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• 2021

Although the compact capacitance model of point tunneling types of tunneling field-effect transistors (TFET) has been proposed, those of line tunneling types of TFETs have not been reported. In this study, a compact capacitance model of an L-shaped TFET (LTFET), a line tunneling type of TFET, is proposed using the previously developed surface potentials and current models of P- and L-type LTFETs. The Verilog-A LTFET model for simulation program with integrated circuit emphasis (SPICE) was also developed to verify the validation of the compact LTFET model including the capacitance model. The SPICE simulation results using the Verilog-A LTFET were compared to those obtained using a technology computer-aided-design (TCAD) device simulator. The current-voltage characteristics and capacitance-voltage characteristics of N and P-LTFETs were consistent for all operational bias. The voltage transfer characteristics and transient response of the inverter circuit comprising N and P-LTFETs in series were verified with the TCAD mixed-mode simulation results.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(2)
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• pp.499-502
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• 2003

This paper presents the voltage source type half bridge lossless auxiliary inductor snubber assisted series capacitor compensated resonant high frequency inverter for induction heated fixing roller in copy machines. This high-frequency inverter treated here can completely achieve zero current soft switching (ZCS) commutation for wide power regulation range under its constant frequency pulse density modulation (PDM) scheme. Its transient and steady-state operating principle is originally presented fur a constant frequency PDM control strategy under a ZCS operation commutation, together with its output effective power regulation characteristics-based on the PDM strategy. The experimental operating performances of this ZCS-PDM high frequency inverter using IGBTs are illustrated as compared with computer simulation ones. Its power losses and actual efficiency are evaluated and discussed on the basis of simulation and experimental results.

• Archives of Pharmacal Research
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• 제19권1호
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• pp.62-65
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• 1996

A homologous series of twenty, hitherto unreported, analogues of 5-halosubstituted $1, 3-Bis(\omega-cyanoalkyl)uracil$acyclic nucleosides were synthesized by the series of alkylation reactions of 5-halouracils with the corresponding chloroacetonitrile, chloropropionitrile, chlorobutyronitrile and 5-chlorovaleronitrile $(Cl-(C_ 2)_n-CN: n=l, 2, 3, 4)\; in\; anhydrous\; DMSO\; (or DMF)/K_2CO_3(or NaH)\; under\; 75^{\circ}C$ temperature. Antitumor activities for the synthesized compounds were determined against three cell lines (FM-3A cell, P-388 cell and U-938 cell lines). The compounds that exhibited moderate activity to significant activity, included la-b, 2a-b, 3a-c, and 4a, whose compounds were active against P-388, FM-3A and U-937 cell lines with the compounds la, lb, and 2a, showing significant antitumor activity (inhibitory concentrations $(IC_{50})$ ranged from 2.2 to $7.0\mug/ml$). Their strucrure-activity relationship did not show any activity differences in their effective chain length (methyl, ethyl, propyl, butyl) in 1, 3-bis(.omega.-cyanoalkyl) uracils.