• The Journal of Asian Finance, Economics and Business
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• v.7 no.11
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• pp.45-53
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• 2020

Past literatures have not studied the impact of real-world events or information on the return and volatility of virtual currencies, particularly on the COVID-19 event, day-of-the-week effect, daily high-low price spreads and information flow rate. The study uses the ARMA-GARCH model to capture Bitcoin's return and conditional volatility, and explores the impact of information flow rate on conditional volatility in the Bitcoin market based on the Mixture Distribution Hypothesis (Clark, 1973). There were 3,064 samples collected during the period from 1^st of January 2012 to 20^th April, 2020. Empirical results show that in the Bitcoin market, a daily high-low price spread has a significant inverse relationship for daily return, and information flow rate has a significant positive relationship for condition volatility. The study supports a significant negative relationship between information asymmetry and daily return, and there is a significant positive relationship between daily trading volume and condition volatility. When Bitcoin trades on Saturday & Sunday, there is a significant reverse relationship for conditional volatility and there exists a day-of-the-week volatility effect. Under the impact of COVID-19 event, Bitcoin's condition volatility has increased significantly, indicating the risk of price changes. Finally, the Bitcoin's return has no impact on COVID-19 events and holidays (Saturday & Sunday).

• Journal of Advanced Navigation Technology
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• v.3 no.2
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• pp.167-173
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• 1999

This paper showed the convergence rate and the performance of interference cancellation using Applebaum and DMI algorithms in adaptive sidelobe canceller. Applebaum algorithm is used widely due to simplicity but it has a slow convergence rate and the problem of eigenvalue spread. DMI algorithm converges rapidly but has computational load and hardware complexity. We compared the performance and complexity using Applebaum and DMI algorithms in Adaptive SLC that requires rapid convergence rate and the performance and conclude that DMI algorithm is more efficient for adaptive SLC.

• The Korean Journal of Food And Nutrition
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• v.34 no.4
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• pp.415-422
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• 2021

This study assessed the preparation and quality characteristics of cookies prepared from Taraxacum coreamm powder (TCP) (0, 2, 4, 6, 8%) substituting wheat flour. The pH of the cookie dough significantly decreased with increasing TCP. However the density of the cookie dough was not significantly different among the test groups. The baking loss rate of the groups with TCP was slightly lower, whereas the moisture content was higher than the control group. The spread factor of the cookies decreased significantly with increasing TCP. The hardness of the cookies increased as TCP increased. In Hunter's color value, the L and a value of the cookies decreased with increasing TCP, while the b value increased. The DPPH radical scavenging activity of the cookies significantly increased with increasing TCP. Based on the above results, this study suggested that TCP can be a good ingredient to increase the functionality of cookies.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.11
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• pp.19-31
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• 1996

Spread spectrum method gurantees good performance in digital communication system under multi-path interference and jamming signals. The purpose of this paper is to develop the wireless modem using DS/SS techinque. The transceiver consists of a spread spectrum DQPSK transmitter and a mtching receiver. The system operates with the chipping rate set to 4 Mcps and the number of chips/symbol at 64, making the data rate 62.5 Kbps using QPSK modilation. The receiver section uses a digital matched filter for fast acquisition of burst signals and uses the comparing the BER of proposed system iwth that of narrow bnd system under various additive white gaussian noises. It is showen that the proposed sysem has better performance than narrow band system. When jamming signals is added to the suggested DS/SS system, we also show that the experimental performance (BER) of the suggested wireless modem is almost same as theroretical performance.

• Journal of Communications and Networks
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• v.8 no.2
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• pp.220-227
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• 2006

In this paper, we present a novel approach to analyze the throughput of direct-sequence spread spectrum multiple access (DS/SSMA) unslotted ALOHA system. In the unslotted system, the departure rate of interfering transmissions is proportional to the number of current interferers that can be regarded as the system state. In order to model this state-dependency, we introduce a two-dimensional state transition model that describes the state transition of the system. This model provides a more rigorous analysis tool for the DS/SSMA unslotted ALOHA systems with both fixed and variable packet lengths. Numerical results reveal that this analysis yields an accurate system performance that coincides with the simulation results. Throughout the analysis we have discovered that the state-dependency of the departure rate causes interference averaging effect in the unslotted system and that this effect yields a higher throughput for the unslotted system than for the slotted system when supported by a strong channel coding.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.11a
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• pp.61-62
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• 2018

On this Study, it conducts the Standards investigation about air leakage of Buildings for performance improvement of Smoke control in Fire. In domestic standards, it is incomplete the Criteria standards of air leakage. Therefore it is considered that won't limit the smoke spread due to stack effect. But in the case of the United States, it conducts the Hot smoke air-Leakage test and it consider that can prevent the Smoke Spread in Compartment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.5
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• pp.939-951
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• 1994

In adaptive equalizers based on least mean squares (LMS) algorithms, the convergence rate is determined by the convariance matrix of an input signal. When the eigenvalue spread of the convariance matrix is close to unity, the convergence rate is quite fast. In this paper, for fast convergence of LMS-based adaptive equalizers we propose a modified reference signal pertinent to the statistical channel. From the theoretical analysis and computer simulation, it is shown that the proposed modification method is quite effective for fast convergence of LMS-based adaptive equalizers.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.06a
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• pp.216-217
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• 2020

As the fire inside the building grows rapidly, ejected flame from an opening occurs due to flashover. As a result, the number of cases where the flame spreads to the exterior of the building and rapidly expands to the upper floor is increasing. In particular, in the case of the fire in the Daebong Green Apartment, Uijeongbu in 2015, it was a case where the flame spread to adjacent buildings due to the opening eruption flame from the first ignited building, causing great damage to three apartments. Therefore, this study is to introduce an international standard under development that estimates the shape and properties of the ejected flame from an opening and quantitatively evaluates the radiant heat flux received by the exterior wall of the building by assuming the occurrence of the ejected flame from an opening.

• Journal of the Korean Society for Railway
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• v.7 no.3
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• pp.180-185
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• 2004

The present study investigates the effect of fire growth model on fire development characteristics in a carriage. The parallel processing version of FDS code is used to simulate the fire driven flow in a carriage and two types of fire growth model which are flame spread model and t$^2$ model are examined for the same geometrical condition. The heat release rates(HRR) of both model are similar each other until 30 s after ignition, but the flame spread model predicts 5 times higher than those of the t$^2$ fire model during the quasi-steady fire period. Maximum heat release rate in the case of flame spread model reaches about to 12 MW at 100 s after fire ignition. Also, various database of fire properties for combustible materials and more elaborate combustion model considering the flame spreading phenomena are required for better predictions of fire development characteristics using numerical simulation.

• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.187-190
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• 2014

An experimental study on downwardly and upwardly spreading flames over slanted electrical wire, which is insulated by Polyethylene(PE), was conducted with applied AC electric field. The result showed that downwardly and upwardly spreading flames with angle of inclination leaned toward burnt side and unburned side, respectively. With applied AC electric fields, size of downwardly spreading flame decreased slightly and that of upwardly spreading flame increased significantly. Flame spread rate showed various trends in terms of inclination, applied voltage and frequency.