• English Language & Literature Teaching
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• v.16 no.3
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• pp.101-117
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• 2010

This study examines whether English users at a U.S. university apply avoidance strategy in using English articles. All participants had learned English for at least 10 years and had used English for at least 15 years at the time of the data collection, so they made an ideal sample to examine the differences between native speakers of English and non-native speakers of English, in terms of avoidance strategy usage of English articles. To examine whether non-native speakers avoid using a certain feature when unsure of the correct usage, the mean differences of each article usage between NS and NNS groups were calculated and compared. On the basis of results showing that there are no statistically significant differences in terms of article usage between the groups, it is concluded that the highly advanced level participants did not use avoidance strategy in English articles, and that the type of English article and the task type did not affect learners' avoidance strategy usage. This research is expected to provide teachers and researchers with information about highly advanced level L2 language speakers' usage patterns with regards to avoidance strategy.

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.1984-1987
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• 2002

This paper describes the design and implementation of a single-chip digitally synthesized 0-35MHz agile function generator. The chip comprises an integrated direct digital synthesizer (DDS) with a 10-bit on- chip digital-to-analog converter (DAC) using an n-well single-poly triple-metal 0.5-$\mu\textrm{m}$ CMOS technology. The main features of the chip include maximum clock frequency of 100 MHz at 3.3-V supply voltage, 32-bit frequency tuning word resolution, 12-bit phase tuning word resolution, and an on-chip 10-bit DAC. The chip provides sinusoidal, ramp, saw-tooth, and random waveforms with phase and frequency modulation, and power-down function. At 100-MHz clock frequency, the chip covers a bandwidth from dc to 35 MHz in 0.0233-Hz frequency steps with 190-ns frequency switching speed. The complete chip occupies 12-mm$^2$die area and dissipates 0.4 W at 100-MHz clock frequency.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.3
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• pp.187-195
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• 1996

This paper proposes two new dynamic CMOS logic styles, called ZMODL (zipper-MODL) and EZMODL (enhanced-ZMODL), which can reduce more area dnd propagation delya than conventional MODL (multiple output domino logic). The 32-bit CLAs(carry look-ahead adder) are designed by ZMODL, EZMODL circuits, and their operations are verified by SPICE 3 with 2$\mu$ double metal CMOS parameters. The results shwo that the CLA designed by EZMODL circuit has achived 32-bit additin time of less than 4.8NS with VDD=5.0V and 8% of transistors cn be redcued, compared to the CLA designed by MODL. The EZMODL logic style can improve the performance in the high-speed computing circuits depending on the degree of recurrence.

• Proceedings of the IEEK Conference
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• 2003.11c
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• pp.191-194
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• 2003

In IEEE 802.11b, Medium Access Control Sublayer consists of DCF (Distributed Coordination Function) and PCF (Point Coordination Function). DCF provides contention based services and PCF provides contention free services for QoS satisfaction. DCF uses CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance) as an access protocol. And PCF uses Polling Scheme. In this paper, a modified New-PCF, which gives weights to channels with heavier traffic load, was suggested. NS-2 simulations were conducted to compare the service performances with original DCF, PCF and the modified New-PCF respectively. Simulation results has shown the increased overall throughput with the proposed New-PCF compared with other cases.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.47-48
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• 2006

In this paper, we analyze the impact of superframe order on the performance of the IEEE 802.15.4 slotted CSMA/CA. A new analytic model to evaluate the saturation throughput is proposed. The new model describes slot time behaviors of the IEEE 802.15.4 slotted CSMA/CA. The proposed model is validated via the comparison with ns-2 simulation results.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.169-170
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• 2006

A band pass filter for the V-band application with unique circuit and structure was designed and implemented using 2-metals, 3-BCB layers. In the mean while the effective electrical conductivity of metal layer was extracted and its value was $4{\times}10^7S/m$. The insertion loss of band pass filter at 60 GHz was 3.0 dB and group delay was below 0.1 ns.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.6
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• pp.810-817
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• 2014

An on-chip current sensor with fast response time for the peak-current-mode buck regulator is proposed. The initial operating points of the peak current sensor are determined in advance by the valley current level, which is sensed by a valley current sensor. As a result, the proposed current sensor achieves a fast response time of less than 20 ns, and a sensing accuracy of over 90%. Applying the proposed current sensor, the peak-current-mode buck regulator for the mobile application is realized with an operating frequency of 2 MHz, an output voltage of 0.8 V, a maximum load current of 500 mA, and a peak efficiency of over 83%.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.6
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• pp.789-796
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• 2014

A CMOS photo detection bias quenching circuit is developed to be used with single photon avalanche photodiodes (SPADs) operating in Geiger mode for the detection of weak optical signals. The proposed bias quenching circuits for the performance improvement reduce the circuit size as well as improve the performance of the quenching operation. They are fabricated in a $0.18-{\mu}m$ standard CMOS technology to verify the effectiveness of this technique with the chip area of only $300{\mu}m^2$, which is about 60 % of the previous reported circuit. Two types of proposed circuits with resistive and capacitive load demonstrated improved performance of reduced quenching time. With a commercial APD by HAMAMATSU, the dead time can be adjusted as small as 50 ns.

• Bulletin of the Korean Chemical Society
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• v.23 no.8
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• pp.1111-1115
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• 2002

The photoluminescence of calixarene crystals has been studied as functions of temperature, time, and concentration. The vibronic bands shift to longer wavelength and become significantly sharper as temperature decreases. The experimental results r eveal that the structural transformation occur during the annealing process. Time-resolved spectra of calixarene at 12 K are monitored. Spectral features, which demonstrate characteristic of energy transfer processes, are not observed. The depopulation of excited state density is mainly controlled by unimolecular decay process dominating other decay processes. The lifetime was found to be 2.6 $\pm$ 0.1 ns. For the case of calixarene mixed with naphthalene, the fluorescence spectrum shows that the band centered at 340 nm lies 2840 $cm^{-1}$ below the relatively broad 310 nm band found for calixarene crystals. The spectra also exhibit that the emission intensity increases with increasing calixarene concentration. The results are evident that the calixarene emission is quenched by the naphthalene. Phosphorescence of calixarene mixed with naphthalene crystals is observed to determine whether the emission is due to naphthalene. The phosphorescence peaks were compared with the ground-state vibrational frequencies of naphthalene and found to be in good agreement. The results indicate that inter-molecular energy transfer occurs between calixarene and naphthalene.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.10a
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• pp.239-244
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• 1996

The aim of this study is to present the elastic modulus equation that suits to a domestic situation to coincide the improved mechanical properties of high-strength concrete. For this purpose, this study collected the laboratory data more than 400 connected with the modulus of elasticity that performed in this country and also compared with the existing equations compressive strength of investigated concrete ranged from 400 to 1, 400kg/$\textrm{cm}^2$. As a result, it could confirm that the existing equations which were proposed by the ACI 363R. CEB-FIP, NS 3473, and New-RC have a tendency to the overestimation in general.