An overview of Silicon Carbide (SiC) Static Induction Transistor (SIT) development is presented. Basic conduction mechanisms are introduced and discussed, including ohmic, exponential, and space charge limited conduction (SCLC) mechanisms. Additionally, the impact of velocity saturation and temperature effects on SCLC are reviewed. The small-signal model, breakdown voltage, power density, and different gate structures are also discussed, before a final review of published SiC SIT results. Published S-band (3-4 GHz) results include 9.5 dB of gain and output power of 120 W, and L-band (1.3 GHz) results include 400 W output power, 7.7 dB of gain, and power density of 16.7 W/cm.

Laser Thomson scattering measurements of electrom temperature and density in a neutral loop discharge (NLD) plasma were performed in order to reveal the electron behavior around the neutral loop (NL). The experimental results were examined by using a simulation model that included effects of a three dimensional electromagnetic field with spatial decay of the RF electric field, and the limitation of the spatial extent of the electron motion and collision effect. From the experiments and modeling of the electron behavior, it was found that NLD plasma posses the electron temeprature $T_{e}$ and density ne peaks around the NL is essential for the formation of plasma. Also, the optimum condition of plasma production could be simply estimated by the calculation of $U_{av}$ and $F_{0}$././.

This paper presents a model for a pin-to-cylinder discharge type ozonizer, which utilizes the superposition of surface discharge and corona discharge operation. By changing the gas flow rate, the discharge power and the number of SDO units, the characteristics of ozone concentration ( $O_{3con}$), ozone generation ( $O_{3g}$) and ozone yield ( $O_{3Y}$) were investigated. Using one SDO unit the maximum values of $O_{3con}$, $O_{3g}$ and $O_{3Y}$ were found as 8100[ppm], 1623[mg/h] and 213[g/kWh] respectively. With two SDO units the corresponding values were found as 12800[ppm], 2893[mg/h] and 248[g/kWh] respectively. Hence using two SDO units the efficiency was improved by 16[%].y 16[%].

For the past five years, Inha University has been observing the electric fields produced by cloud-to-ground return strokes. This paper presents the summary of most recent results. Statistics on the zero-to-peak rise time, the zero-to-zero crossing time and the amplitude ratio of the second peak in the opposite polarity to the first peak were examined. The radiation electric fields produced by distant cloud-to-ground return strokes were substantially same pattern. The first return stroke field starts with a slowly increasing front and rises abruptly to peak. The rising portions of the electric fields produced by cloud-to-ground return strokes last 1 $mutextrm{s}$ to a few $mutextrm{s}$. The mean values of the zero-to-peak rise times of electric fields were 5.72 $mutextrm{s}$ and 4.12 $mutextrm{s}$ for the positive and the negative cloud-to-ground return strokes, respectively. The mean of the zero-to-zero crossing time for the positive return strokes was 29.48 $mutextrm{s}$ compared with 38.54 $mutextrm{s}$ for the negative return strokes. The depths of the dip after the peak of return stroke electric fields also have the dependence on the polarity of cloud-to-ground return stroke, and the mean values for the positive and negative cloud-to-ground return strokes were 33.55 and 28.19%, respectively.

We describe the pulse forming of pulsed $CO_2$laser using multi-pulse superposition technique. A various pulse length, high duty cycle pulse forming network(PFN) is constructed by time sequence. That is, this study shows a technology that makes it possible to make various pulse shapes by turning on SCRs of three PFN modules consecutively at a desirable delay time with the aid of PIC one-chip microprocessor. The power supply for this experiment consists of three PFN modules. Each PFN module uses a capacitor, a pulse forming inductor, a SCR, a High voltage pulse transformer, and a bridge rectifier on each transformer secondary. The PFN modules operate at low voltage and drive the primary of HV pulse transformer. The secondary of the transformer has a full-wave rectifier, which passes the pulse energy to the load in a continuous sequence. We investigated laser pulse shape and duration as various trigger time intervals of SCRs among three PFN modules. As a result, we can obtain laser beam with various pulse shapes and durations from about 250 $mutextrm{s}$ to 600 $mutextrm{s}$.

In this research, we synthesized various photo-crosslinkable polyimide based polymers. The control of pretilt angles for a nematic liquid crystal (NLC) using the photodimerization method on the photopolymers was studied. A good thermal stability of the photopolymers was measured by thermogravimetric analysis (TGA) measurement until 450C. High pretilt angles of the NLC were otained by polarized UV exposure on the photopolymers containing biphenyl (BP), decyl (de), and cholesteryl (chal) groups, respectively. However, low pretilt angles of the NLC were measured by polarized UV exposure on the photopolymers containing fluorine and chalcone groups. The high NLC pretilt angles generated are attributable to the biphenyl and alkyl moieties, and the photodimerized chalocone group of the photopolymers. Additionally, good voltage-transmittance and response time characteristics were observed by UV exposure on the photopolymers.

The fluorescence emission spectrum of Cr$^{3+}$ doped BeAl$_{6}$ O$_{10}$ crystals at 300 K contains a broad band, three R-like lines and another emission lines. It has been identified by a lifetime resolution spectroscopic technique that there are three kinds of single-Cr$^{3+}$ centers, Cr(I), Cr(II), Cr(III), in this crystal. Cr(I) and Cr(II) are high-crystal field centers responsible for the three main "R-lines", and Cr(III) is a low-crystal field center responsible for the main broad band emission. The structures of these luminescent centers are reported.ted.

The residual DC phenomena in the in-plane switching(IPS)-liquid crystal display(LCD) by the voltage-transmittance (V-T) and capacitance-voltage (C-V) hysteresis method on rubbed polyimide (PI) surfaces were studied. We found that the residual DC voltage in the IPS-LCD was decreasing with the increasing concentration of cyano LCs. The residual DC voltage of the IPS-LCD can be improved by the high polarity of cyano LCs.

The functionalized dendrimer containing 48 azobenzene was synthesized. Many isolated featureless domains were explicitly observed even at the air/water interface. Also, these monolayers were representatively observed, showing the change of surface pressure with irradiation time and wavelength. In AFM images, larger domains irregularly shaped structures on the top, while smaller ones were free from such defects. In the optical absorption spectra of the monolayer films by UV irradiation and heat treatment, only the photoiosmerization of the G4-48 Azo monolayers was observed, revealing a decrease of absorbance peaks without any change of the spectral shape. This suggests that the functional group and the symmetric chain affect optical behavior and morphological change.

In this paper, we presented a novel structure of microstrip directional coupler for realizing the high directivity characteristic and tight coupling. The achievement of the high directivity with microstrip configuration was carried out by matching the even and odd mode effective phase velocities. By using 2-dimensional finite element (FE) calculations, the phase velocity for each mode and design parameters were extracted for given dimensions. Based on the extracted design parameter with phase-matched condition, we designed and fabricated 3dB and 4.7dB directional coupler at 2.0GHz. Experimental results of microstrip coupler show good performance with excellent isolation characteristics.