• Journal of Advanced Marine Engineering and Technology
• /
• v.31 no.6
• /
• pp.777-783
• /
• 2007

In this work, a highly integrated downconverter MMIC employing HBT(heterojunction bipolar transistor) was developed for application to one chip tranceiver solution of Ku-band commercial wireless communication system. The downconverter MMIC (monolithic microwave integrated circuit) includes mixer filter. amplifier and input/output matching circuit. Especially, spiral inductor structures employing SiN film were used for a suppression of LO and its second harmonic leakage signals. Concretely, they were properly designed so that the self-resonance frequency was accurately tuned to LO and its second harmonic frequency, and they were integrated on the downconverter MMIC.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.32A no.3
• /
• pp.25-37
• /
• 1995

The phenomenological loss equivalence method incorporated into the wideband lossy transmission line model is applied to the characterization of high desity digital transmission lines. The pulse propagation characteristics are analyzed using the calculated frequency characteristics and the discrete Fourier transformation. This approach has been verified by comparing the calculated frequency characteristics with the FEM and the esperimental results. This method is very suitable for computer-aided analysis of high density/high speed interconnection circuits because of the simple calculation as well as the calculation accuracy. We have found that pulse ftransmission speed and dispersion of hgih density digital transmission lines can be optimized by managing the conductor and dielectric losses in addition to the impedance matching.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.3 no.3
• /
• pp.139-144
• /
• 2003

We report the results of extensive mixed mode simulations and theoretical analysis to quantify the contribution of the edge direct tunneling (EDT) current on the total gate leakage current of 80nm NMOSFET with SiO2 gate dielectric. It is shown that EDT has a profound impact on basic analog circuit building blocks such as sample-hold (S/H) circuit and the current mirror circuit. A transistor design methodology with zero gate-source/drain overlap is proposed to mitigate the EDT effect. This results in lower voltage droop in S/H application and better current matching in current mirror application. It is demonstrated that decreasing the overlap length also improves the basic analog circuit performance metrics of the transistor. The transistor with zero gate-source/drain overlap, results in better transconductance, input resistance, output resistance, intrinsic gain and unity gain transition frequency.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
• /
• 2001.11a
• /
• pp.257-261
• /
• 2001

This paper presents the implementation of wide-band RFIC amplifier operating from near 50MHz to 3GHz using Tachyonics SiGe HBT foundry. Voltage shunt feedback is used for the flat gain and the broad band impedance matching. Initial design parameters are calculated using the low frequency small signal analysis. Since the HBT model was not available at the design time, discrete tuning board was made for fine tuning in the low frequency range. Fabricated amplifier shows 12dB gain with 1dB fluctuation and PldB reaches 15dBm at 850MHz.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.57 no.5
• /
• pp.816-820
• /
• 2008

The RF inductive discharge of inductively couples plasma (ICP) continues to attract growing attention as an effective plasma source in many industrial applications, the best known of which are plasma processing and lighting technology. Although most practical ICPs operate at 13.56 [MHz] and 2.65 [MHz], the trend to reduce the operating frequency is clearly recognizable from recent ICP developments. In an electrodeless fluorescent lamp, the use of a lower operating frequency simplifies and reduces cost of RF matching systems and RF generators and can eliminate capacitive coupling between the inductor coil and plasma, which could be a strong factor in wall erosion and plasma contamination. In this study, We discussed simulation and experimental results when changing ferrite position in antenna.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.8 no.1
• /
• pp.213-219
• /
• 2004

This paper proposes speaker recognition algorithm which includes the pitch parameter for the peak and valley. The time-frequency hybrid method for pitch extraction is valuable in that it can improve resolution in the time domain and accuracy in the frequency domain at the same time. It makes reference pattern using membership function and performs vocal track recognition of common character using fuzzy pattern matching in order to include time variation width for non-linear utterance for proposed method, speaker recognition experiments are carried out using vowels and number sounds.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.25 no.1B
• /
• pp.48-55
• /
• 2000

The design techniques of an asymmetric TEM (ATEM) cell for calibrating E/H filed probes are presented in this paper. The authors describe the techniques to obtain not only the arbitrary frequency and second resonant frequency, but also the test space with $\pm$2dB filed uniformity. We could design an ATEM cell that the measured data, electric filed distribution inside the cell, impedance matching and resonant frequencies, agree with the calculated results.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
• /
• 2002.08a
• /
• pp.14-23
• /
• 2002

Wave breaking and breaking wave-induced hydrodynamics are very important subjects in the field of coastal and ocean hydrodynamics and engineering. In the coastal zone, a submerged breakwater has been increasingly popular, since it is one of nature-matching structures with multi- functions such as (1) wave energy dissipation by wave breaking and friction, (2) oxygen supply to sea by wave breaking and breaking wave, (3) water purification by entrained air bubbles, (4) keeping. good seascape. and (5) good habitat for sea livings. Recently, the breaking wave-induced high frequency pressure over a submerged breakwater is said to have a function of gathering sea livings around the structure, which has encouraged the construction of the submerged breakwater in coastal zone. (omitted)

• Phonetics and Speech Sciences
• /
• v.1 no.3
• /
• pp.73-85
• /
• 2009

This paper introduces the technique of synthesizing and evaluating human utterances with exaggerated or atypical prosody. Prosody exaggeration can be implemented by manipulating either the fundamental frequency (F0) contour, the segmental durations, or the intensity contour of an utterance. Of these three prosodic elements, two or more can be exaggerated at the same time. The algorithms of synthesis and evaluation were suggested. Learner utterances exaggerated in each of the three prosodic features were evaluated with respect to their original native versions in terms of the differences in their F0 contours, the segmental durations, and the intensity contours. The measure of differences was the Euclidean distance metric between the matching points in their F0 and intensity contours. The measure was calculated after the exaggerated learner utterances were aligned by the segments and rendered identical to their native version in terms of their segmental durations. For the evaluation of the segmental durations, no prior modifications were made in durations and the same measure was used. The results from the pilot experiment suggest the viability of this measure in the evaluation of learner utterances with atypical prosody with respect to their native versions.

• Journal of the Optical Society of Korea
• /
• v.13 no.1
• /
• pp.158-165
• /
• 2009

We present cross-correlation frequency-resolved optical gating (XFROG) measurements of supercontinuum pulses generated by using a photonic crystal fiber (PCF), and ultraviolet (UV) pulses generated by frequency doubling of infrared ultra-short pulses. Since supercontinuum pulses have broad spectra, XFROG measurement typically requires using an extremely thin nonlinear crystal which has a thickness of sub-ten microns. Instead of using such a thin crystal, we employed a relatively thick crystal which was mounted on a galvanometer in order to achieve a phase-matching over the whole spectral bandwidth of the supercontinuum pulses by a crystal-dithering technique. Experimental results of the retrieved phase and intensity were in fair agreement with the independently measured data.