• Proceedings of the Korean Magnestics Society Conference
• /
• 2000.09a
• /
• pp.584-584
• /
• 2000

Electronic structures of ordered Fe$_3X (X = Al, Si), and their derivative ternary alloys of Fe_2TX (T = 3d transition metal) have been investigated by using the linearized muffin-tin orbital (LMTO) band method. The role of the coupling between substituted transition metal and its neighbors is investigated by calculating the magnetic moments and local density of states (LDOS). It is shown that it is essential to include the coupling beyond nearest neighbors in obtaining the magnetic moment of Fe alloy. The preferential sites of T impurities in Fe_3X are determined from the total energy calculations. The derivative ternary alloys of Fe_2TX have characteristic electronic structures of semi-metal for Fe_2VAI and (nearly) half-metal for Fe_2TAI (T = Cr, Mn) and Fe_2TSi (T = V, Cr, Mn)

• The Transactions of the Korean Institute of Power Electronics
• /
• v.26 no.5
• /
• pp.349-356
• /
• 2021

Permanent magnet synchronous motors are mainly used in the traction of electric vehicle and home application products including air-conditioners and refrigerators. For sensorless control without rotor position sensors, I-F control is applied for initial starting at low speeds, and mode is changed to sensorless control when the rotor speed is sufficiently accelerated for estimating rotor position. When the mode is changed to the sensorless control from the open-loop starting, the initial integral value of the speed controller should be considered by load condition; otherwise, the transition to sensorless control may fail. The sensorless transfer algorithm of PM synchronous motor based on load condition for smooth transition is proposed. The performance of the proposed sensorless transfer algorithm was verified by experiments.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2006.11a
• /
• pp.83-84
• /
• 2006

For phase transition method, good recording sensitivity, low heat radiation, fast crystallization and hi-resolution are essential. Also, A retention time is very important part for phase transition. In our presentation wall, we chose Ge-Se-Te material to use a Se material which has good optical sensitivity than Sb. A Ge-Se-Te sample was fabricated and Irradiated with He-Ne laser and DPSS laser to investigate a reversible phase change by light.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.27 no.2
• /
• pp.97-103
• /
• 2014

Phase transition properties of the copolymer films of polyvinylidene fluoride (PVDF) and trifluoroethylene(TrFE), P(VDF-TrFE), were studied with X-ray diffraction (XRD) and polarization modulated ellipsometry (PME). XRD studies on both Langmuir-Blodgett (LB) films and spin coated films exhibit conversions from ferroelectric phase to paraelectric phase at $108{\pm}2^{\circ}C$ on heating and paraelectric phase to ferroelectric phase at $78{\pm}2^{\circ}C$ on cooling. The presence of the ferroelectric-paraelectric phase transition is also confirmed by the PME technique for the first time in this study. PME was proved to be a very sensitive tool in the measurement of the structural changes at the nano-thickness films.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2007.06a
• /
• pp.453-453
• /
• 2007

Electrodeless fluorescent lamp exhibit two modes of operation: a low density mode in which the power is capacitively coupled to the plasma and which is known as the E-mode, and a higher density mode which is an inductive discharge known as the H-mode. The transition between these two(E to H) mode exhibits hysteresis. It is observed that transition currents change at different frequencies and hysteresis exists not only between the starting and minimum maintaining currents of the electromagnetic mode (H mode) discharge but also between the starting and minimum maintaining currents of the electrostatic mode (E mode) discharge. Hysteresis effect can be important role in dimming system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2000.07a
• /
• pp.491-494
• /
• 2000

Conductive Langmuir-Blodgett(LB) films have recently attracted much interest from the viewpoint of ultrathin film conductors at the molecular level. The result shows that the Maxwell-displacement-current(MDC) measuring technique is useful in the detection of phase-transition over the entire range of molecule areas. At the liquid-solid phase transition, a striking feature in the present current measurement was observed; the I-A isotherm for a DPPC monolayer has sharp bend. Dynamic behavior of monolayers in the presence of an external field was also investigated using the current-measuring technique. Dynamic behavier of DPPC monolayer was measured by displacement current when the molecules are stimulated by pressure velocity. As result, it is known that current is generated of higher current pe마 as compression velocity become faster. Also, in order to clarify the reorganization of the lipid monolayers, it is instructive to plot the relationship between I and 1/$A^2$.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.24 no.5
• /
• pp.372-378
• /
• 2019

This study proposes a new zero-current-zero-voltage-transition (ZCZVT) boost-flyback converter using a soft switching auxiliary circuit. The proposed converter integrates the boost and flyback converters to increase the voltage with a low duty ratio. The main and auxiliary switches turn the ZCZVT conditions on and off. Thus, the proposed converter has high efficiency. The voltage gain at the steady state is derived, and the inductor volt-second balance and the design guidelines are presented. Finally, the performance of the proposed converter is validated by experimental results from a 200 W, 30 V DC input, 400 V DC output, and 200 kHz boost-flyback converter prototype.

• ETRI Journal
• /
• v.45 no.6
• /
• pp.974-981
• /
• 2023

This paper presents a transition-limited pulse-amplitude modulation (TLPAM) signaling method to enable a high data rate and robust wireline communications. TLPAM signaling addresses the impact of high intersymbol interference (ISI) ratios in conventional M-ary PAM signaling methods by limiting the maximum voltage transition level between adjacent symbols. The implementation of a TLPAM signaling encoder is realized by setting back the most significant bits (MSBs) in the queue. The correlation between TLPAM's maximum transition level, effective data rate, and eye width/height is analyzed with various channel loss parameters, followed by characterization and measurement results with a realistic channel setup. The analysis and experimental results reveal the effectiveness of the proposed TLPAM signaling scheme for achieving a high data rate with minimal interference.

• Journal of Advanced Navigation Technology
• /
• v.17 no.6
• /
• pp.658-663
• /
• 2013

In this paper, a microstrip line implementation using via transition and its application of multilayer compact ring hybrid coupler are presented. This transition is the sandwich structure with via hole to connect two microstrip lines in different layer. For designing a compact RF/Microwave passive circuit, the microstrip line using via-hole transition is proposed to reduce a size of microwave circuit with long transmission line. For the validation of the microstrip line with via-hole transition, the multilayer ring hybrid coupler is implemented at center frequency of 2 GHz. The measured performances are in good agreement with simulation results and about 50% size reduction compare to conventional ring hybrid coupler.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.46 no.5
• /
• pp.15-24
• /
• 2009

This paper proposes an effective low power BIST architecture using the pattern mapping method for 100% fault coverage and the transition freezing method for making high correlative low power patterns. When frozen patterns are applied to a circuit, it begins to find a great number of faults at first. However, patterns have limitations of achieving 100% fault coverage due to random pattern resistant faults. In this paper, those faults are covered by the pattern mapping method using the patterns generated by an ATPG and the useless patterns among frozen patterns. Throughout the scheme, we have reduced an amount of applied patterns and test time compared with the transition freezing method, which leads to low power dissipation.