• Proceedings of the Korea Society of Information Technology Applications Conference
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• 2005.11a
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• pp.99-102
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• 2005

In the paper, a proposed VCO based on bondwire inductances and nMOS varactors was implemented in a standard $0.25\;{\mu}m$ CMOS process. Using the new drain current model and a propagation delay time model equations, the operation speed of CMOS gate will predict the dependence on the load capacitance and the depth of oxide, threshold voltage, the supply voltage, the channel length. This paper describes the result of simulation which calculated a gate propagation delay time by using new drain current model and a propagation delay time model. At the result, When the reverse bias voltage on the substrate changes from 0 voltage to 3 voltage, the propagation delay time is appeared the delay from 0.8 nsec to 1 nsec. When the reverse voltage is biased on the substrate, for reducing the speed delay time, a supply voltage has to reduce. The $g_m$ value of MOSFET is calculated by using new drain current model.

• Journal of Positioning, Navigation, and Timing
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• v.11 no.1
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• pp.23-28
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• 2022

The eLoran system is a high-power terrestrial navigation system that is recognized as the most appropriate alternative to complement the GNSS's vulnerability to radio frequency interference. Accordingly, Korea has conducted eLoran technology development projects since 2016. The eLoran system developed in Korea provides 20 m positioning accuracy to maritime user in Incheon and Pyeongtaek harbor. To accurately calculate the position with the eLoran signal, it is necessary to apply a compensation method that mitigates the propagation delay. In this paper, we develop the compensation method to mitigate the eLoran signal propagation delay and evaluate the positioning performance in Incheon harbor. The propagation delay due to the terrain characteristics is pre-surveyed and stored in the user receiver. Real-time fluctuations in propagation delay compared to the pre-stored data are mitigated by the temporal correction generated at a nearby differential Loran station. Finally, two performance evaluation tests were performed to verify the positioning accuracy of the Korean eLoran system. The first test took place in December 2020 and the second in April 2021. As a result, the Korean eLoran service has been confirmed to provide 20 m location accuracy without GPS.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.882-886
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• 2005

As the TFT-LCD panels become larger and provide higher resolution, the distributed capacitive and resistive lines induce the propagation delay, reduce the TFT-on time and deteriorate the pixel chargingratio. A number of the compensation methods, like the H-LDC (Horizontal Line Delay Compensation), have been proposed to compensate the propagation delay of the large and high resolution panels [1]. These methods, however, require the comparatively accurate gate propagation delay estimates at each column driver. In this paper, by observing the actual gate and data waveform from 15-inch XGA TFT-LCD panels, we could predict the propagation delay along the row and column line.

• Journal of Mechanical Science and Technology
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• v.18 no.11
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• pp.2058-2065
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• 2004

A light collecting probe named Multi-color Integrated Cassegrain Receiving Optics (MICRO) is applied to spark-ignited spherical spray flames to obtain the flame propagation speed in freely falling droplet suspension produced by an ultrasonic atomizer. Two MICRO probes are used to monitor time-series signals of OH chemiluminescence from two different locations in the flame. By detecting the arrival time difference of the propagating flame front, the flame propagation speed is calculated with a two-point delay-time method. In addition, time-series images of OH chemiluminescence are simultaneously obtained by a high-speed digital CCD camera to ensure the validity of the two-point delay-time method by the MICRO system. Furthermore, the relationship between the spray properties measured by phase Doppler anemometer (PDA) and the flame propagation speed are discussed with three different experimental conditions by changing the fuel injection rate. It was confirmed that the two-point delay-time method with two MICRO probes is useful and convenient to obtain the flame propagation speed and that the flame propagation speed depends on the spray properties.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.05a
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• pp.78-81
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• 1999

The position and time errors of a conventional L1-band GPS receiver (1575.42MHz) are known to be about 100 m and 70 ns, respectively. These errors are mainly due to the propagation delay of GPS satellite signals through ionosphere. Various L1/L2 dual-band GPS receivers are normally used to compensate for those position and time errors by detecting an accurate propagation delay. These receivers detect the propagation delay difference between the L1 and L2 signals based on the fact that the propagation delay through ionosphere is dependent on frequency and, from which, calculate an accurate propagation delay of the GPS signals through ionosphere. In this paper, we analyzed the architecture of a L1/L2 dual-band CPS receiver by high-level simulations with Synopsys's COSSAP Tool.

• The Journal of the Acoustical Society of Korea
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• v.34 no.6
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• pp.463-469
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• 2015

In this paper, we propose an underwater propagation delay-aware medium access control protocol and evaluate the performance of the proposed protocol. In the proposed propagation delay-aware medium access control protocol, a sink node can restore the received RTS frames that are not piled up in a slot time. We analyze and compare the performance of the proposed underwater propagation delay-aware medium access control protocol with that of the conventional medium access control protocol in various environments.

• The Journal of the Acoustical Society of Korea
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• v.19 no.5
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• pp.53-59
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• 2000

In this paper, considering configuration of the earth and environment of country, it is classified a radio propagation environment Multipath propagation measuring system based on PN code correlation detection method is built to study a wave propagation characteristics of 1.95GHz. Considering the characteristic artificial structure of country, Cihwa plant superintendent area has been selected for basic and accurate measurement a radio propagation characteristic. The experiments are carried out with respect to the RMS delay Spread and the received power in the two kind of geographical areas, LOS (Line of Sight) and N-LOS (Non Line of Sight). The measurement result of that received power of LOS area is -1.6∼-28.8dBm, RMS delay spread is 0.023㎲∼0.22㎲ and received power of N-LOS area is 16∼36.5dBm and RMS delay spread is 0.068∼0.37㎲.

• Journal of ILASS-Korea
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• v.3 no.1
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• pp.19-26
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• 1998

The effect of mixture component makes a nelay time and a long total combustion period $\tau_{p\;max}$. The flame propagation delay $\tau_{df}$ was determined by the record of current ion. The pressure release delay $\tau_{dp}$ and $\tau_{p\;max}$ were determined by the indicated pressure diagram in constant volume of the combustion chamber. The results are as follows: 1) The ignition delay $\tau_t$ time takes the minimum value around $\Phi=1.15$. 2) $\tau_{df}$ and $\tau_t$ time increased according to the increases of the concentrated dilution gases, because the adiabatic flame temperature decreased due to the increases of the heat capacity. But dilution gases have little effect on flame nucleus formation delay 3) The relation between $\tau_t$ time and reciprocal laminar burning velocity is almost linear. 4) The increase of the propagation length is accompanied with increased ratio of the $\tau_{df},\;\tau_{dp},\;\tau_{t},\;\tau_{p\;max}$.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.1
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• pp.50-60
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• 2015

A Block-Time-Bounded Time Division Multiple Access (BTB-TDMA) medium access control protocol, which estimates the propagation delay of nodes according to their location and moving velocity information, has been proposed for underwater acoustic networks. BTB-TDMA provides nodes with their transmission schedules by a time block that is a time unit, newly designed for BTB-TDMA. In this paper, we investigate how the receiver collision, that is induced by the asymmetry between node's uplink and downlink propagation delay due to its mobility, affects the performance of BTB-TDMA. To do this, we analytically obtain the collision rate, the channel access delay, and the channel utilization by considering the asymmetry of propagation delay. Then, simulations are extensively performed with respect to the length of a time block by varying the number of nodes, the network range, and the node's velocity. Thus, the simulation results can suggest performance criteria to determine the optimal length of a time block which minimizes the collision rate and concurrently maximizes the channel access delay and the channel utilization.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.1
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• pp.87-96
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• 2013

Influence propagation is an important research issue in social networks. Influence propagation means that the status or the disposition of nodes get changed by new idea, information and gossip propagated by other nodes. Influenced nodes also make other nodes influenced across the network. The influence propagation problem based on 'word of mouth' referral is to find most influential nodes set in networks to maximize influence. In this paper, we study the influence measuring and finding most influential nodes set in Delay-Tolerant Networks. It is difficult to measure exact influential power in Delay-Tolerant networks where network topology is not stable due to the nodal mobility. In this paper, we propose a distributed scheme that each node constructs $k$-clique community structure and estimates local influential power in Delay-Tolerant Networks. Simulation results show that the influential nodes information estimated by proposed scheme is in agreement with a global view of influential nodes information.