• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.07a
• /
• pp.396-399
• /
• 2003

4H-SiC un diodes with field limiting rings(FLRs) were fabricated and characterized. The dependences of reverse breakdown voltage on the number of FLRs, the distance between p-base main junction and first FLR, and activation temperatures, were investigated. Al and B ions were implanted and activated at high temperature to form p-base region and p+ region in the n-epilayer. We have obtained up to 1782V of reverse breakdown voltage in the un diode with two FLRs on loom thick epilayer. The differential on-resistances of the fabricated diode are $5.3m{\Omega}cm^2$ at $100A/cm^2$ and $2.7m{\Omega}cm^2$ at $1kA/cm^2$, respectively. All pn diodes with FLRs have higher avalanche breakdown voltages than that of diode without an FLR. Regardless of the activation temperature, the un diode with a FLR located 5um apart from main junction has the highest mean breakdown voltage around 1600V among the diodes with one ring. On the other hand, the pn diode with two rings showed different behavior with activation temperature. It reveals that high voltage SiC pn diodes with low on-resistance can be fabricated by using the FLR edge termination.

• Journal of the Semiconductor & Display Technology
• /
• v.22 no.3
• /
• pp.155-160
• /
• 2023

The potential performance benefits of Silicon Carbide(SiC) MOSFETs in high power, high frequency power switching applications have been well established over the past 20 years. In the past few years, SiC MOSFET offerings have been announced by suppliers as die, discrete, module and system level products. In high-voltage SiC vertical devices, major design concerns is the edge termination and cell pitch design Field Limiting Rings(FLR) based structures are commonly used in the edge termination approaches. This study presents a comprehensive analysis of the impact of variation of FLR and JFET region on the performance of a 3.3 kV SiC MOSFET during. The improvement in MOSFET reverse bias by optimizing the field ring design and its influence on the nominal operating performance is evaluated. And, manufacturability of the optimization of the JFET region of the SiC MOSFET was also examined by investigating full-map electrical characteristics.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.33A no.6
• /
• pp.136-143
• /
• 1996

A simple analytic model for the planar junctions with multiple foating field limiting rings(FLR) is presented which yields analytic expressions for the breakdown voltage and optimum ring spacings. the normalized potential of each ring is derived as a function of the normalized depletion width and the ring spacing. Based on the assumption that the breakdwon occurs simulataneously at cylindrical junctions of FLR structure where the peak sruface electric fields are equal, the optimum ring spacings are determined. The resutls are in good agreement with the simulations obtained from two dimensional device simulation program MEDICI and with the experimental data reported. The normalized experessions allow a calculation of breakdown voltage and optimum spacing over a broad range of junction depth and background doping levels.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.44 no.4
• /
• pp.490-495
• /
• 1995

A bipolar junction transistor which exihibits 1000V breakdown voltage is designed and fabricated using FLR (Field Limiting Rings). Three dimensional effects on the breakdown voltage is investigated in the cylindrical coordinate and the simulation results are compared with the results in the rectangular coordinate. Breakdown voltage of the device with 3 FLR is simulated to be 1420V in the cylindrical coordinate while it is 1580V in rectangular coordinate. Bipolar junction transistor has been fabricated using the epitaxial wafer of which resistivity is 86 .OMEGA.cm and thickness is 105 .mu.m. Si$_{3}$N$_{4}$ and glass are employed for the passivation. Breakdown of the fabricated device is measured to be 1442V which shows better greement with the simulation results in cylindrical coordination.

• Proceedings of the KIEE Conference
• /
• 2003.10a
• /
• pp.312-315
• /
• 2003

In recent, there have been several developments in lamp technology that promise savings in electrical power consumption and improved quality of the lighting space. Above all, the advantage of ring-shaped electrodeless fluorescent lamp is the removal of internal electrodes and heating filaments that are a light-limiting factor of conventional fluorescent lamps. The ring-shaped electrodeless lamp is intended as a high efficacy replacement for the incandescent reflector lamp in many applications. Therefore, the life time of ring-shaped electrodeless fluorescent lamps is substantially higher than that of conventional fluorescent lamps and last up to 60,000 hours. In this paper, maxwell 3D finite element analysis program (Ansoft) was used to obtain electromagnetic properties associated with the coil and nearby structures. The electromagnetic emitting properties were presented by 3D simulation software operated at 250[kHz] and some specific conditions.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.52 no.6
• /
• pp.257-260
• /
• 2003

We have proposed the junction termination structure of IGBT (Insulated Gate Bipolar Transistor) by employing trench and FLR (Field Limiting Ring), which decrease the junction termination area at the same breakdown voltage. Our proposed junction termination structure, trench FLR is verified by numerical simulator MEDICI. In 600V rated device, the junction termination area is decreased 20% compared with that of the conventional FLR structure. The breakdown voltage of trench FLR with 4 trenches is 768 V, 99 % of ideal parallel-plane junction(1-D) $BV_ceo$.

• Bulletin of the Korean Mathematical Society
• /
• v.60 no.3
• /
• pp.829-844
• /
• 2023

In this paper, we present a new construction for self-dual codes that uses the concept of double bordered construction, group rings, and reverse circulant matrices. Using groups of orders 2, 3, 4, and 5, and by applying the construction over the binary field and the ring F₂ + uF₂, we obtain extremal binary self-dual codes of various lengths: 12, 16, 20, 24, 32, 40, and 48. In particular, we show the significance of this new construction by constructing the unique Extended Binary Golay Code [24, 12, 8] and the unique Extended Quadratic Residue [48, 24, 12] Type II linear block code. Moreover, we strengthen the existing relationship between units and non-units with the self-dual codes presented in [10] by limiting the conditions given in the corollary. Additionally, we establish a relationship between idempotent and self-dual codes, which is done for the first time in the literature.

• Bulletin of the Society of Naval Architects of Korea
• /
• v.27 no.3
• /
• pp.38-46
• /
• 1990

A numerical solution method of the boundary integral equation for axisymmetric potential flows is presented. Those are represented by ring source and ring vorticity distribution. Strengths of ring source and ring vorticity are approximated by linear functions of a parameter $\zeta$ on a segment. The geometry of the body is represented by a cubic B-spline. Limiting integral expressions as the field point tends to the surface having ring source and ring vorticity distribution are derived upto the order of ${\zeta}ln{\zeta}$. In numerical calculations, the principal value integrals over the adjacent segments cancel each other exactly. Thus the singular part proportional to $\(\frac{1}{\zeta}\)$ can be subtracted off in the calculation of the induced velocity by singularities. And the terms proportional to $ln{\zeta}$ and ${\zeta}ln{\zeta}$ can be integrated analytically. Thus those are subtracted off in the numerical calculations and the numerical value obtained from the analytic integrations for $ln{\zeta}$ and ${\zeta}ln{\zeta}$ are added to the induced velocity. The four point Gaussian Quadrature formula was used to evaluate the higher order terms than ${\zeta}ln{\zeta}$ in the integration over the adjacent segments to the field points and the integral over the segments off the field points. The root mean square errors, $E_2$, are examined as a function of the number of nodes to determine convergence rates. The convergence rate of this method approaches 2.

• Bulletin of the Korean Chemical Society
• /
• v.35 no.7
• /
• pp.2065-2071
• /
• 2014

${\beta}$-Secretase (beta-amyloid converting enzyme 1 [BACE1]) is involved in the first and rate-limiting step of ${\beta}$-amyloid ($A{\beta}$) peptides production, which leads to the pathogenesis of Alzheimer's disease(AD). Therefore, inhibition of BACE1 activity has become an efficient approach for the treatment of AD. Ligand-based and docking-based 3D-quantitative structure-activity relationship (3D-QSAR) studies of acyl guanidine analogues were performed with comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) to obtain insights for designing novel potent BACE1 inhibitors. We obtained highly reliable and predictive CoMSIA models with a cross-validated $q^2$ value of 0.725 and a predictive coefficient $r{^2}_{pred}$ value of 0.956. CoMSIA contour maps showed the structural requirements for potent activity. 3D-QSAR analysis suggested that an acyl guanidine and an amide group in the $R_6$ substituent would be important moieties for potent activity. Moreover, the introduction of small hydrophobic groups in the phenyl ring and hydrogen bond donor groups in 3,5-dichlorophenyl ring could increase biological activity.

• Journal of Advanced Marine Engineering and Technology
• /
• v.38 no.1
• /
• pp.86-91
• /
• 2014

In the field of shipbuilding and marine, electrical power system is that each of the distributed bus bars is connected electrically. In this way, it would be appropriate to recognize as grid-connecting rather than the redundant bus. Short-circuit capacity of the electric power system will be increased proportionally which is due to the addition of the bus. The increase of short-circuit capacity needs high initial cost associated with equipment and can generate the blackout when the equipment with a physically connected to the bus occurs the electric failure. In order to solve these problems, marine electrical power system in which current limiting reactor has been applied is classified according to the network topology, bus network, star network and ring network. And short circuit analysis for each network is performed by the fault types. The results are presented pros and cons compared to each other.