• Asia-Pacific Journal of Business
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• v.14 no.3
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• pp.221-240
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• 2023

Purpose - This paper investigates how business cycle impacts on corporate credit spreads since global financial crisis. Furthermore, it tests how the impact changes by the phase of the cycle. Design/methodology/approach - This study collected dataset from Barclays Global Aggregate Bond Index through the Bloomberg. It conducted multi-regression analysis by projecting business cycle using Hodrick-Prescott filtering and various cyclical variables, while ran dynamic analysis of 5-variable Vector Error Correction Model to confirm the robustness of the test. Findings - First, it proves to be statistically significant that corporate credit spreads have moved countercyclicaly since the crisis. Second, It indicates that the corporate credit spread's countercyclicality to the macroeconomic changes works symmetrically by the phase of the cycle. Third, the VECM supports that business cycle's impact on the spreads maintains more sustainably than other explanatory variable does in the model. Research implications or Originality - It becomes more appealing to accurately measure the real economic impact on corporate credit spreads as the interaction between credit and business cycle deepens. The economic impact on the spreads works symmetrically by boom and bust, which implies that the market stress could impact as another negative driver during the bust. Finally, the business cycle's sustainable impact on the spreads supports the fact that the economic recovery is the key driver for the resilience of credit cycle.

• Journal of Power System Engineering
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• v.17 no.5
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• pp.100-111
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• 2013

Indoor real-time positioning for multiple targets is required to realize human-robot symbiosis. This study firstly presents positioning accuracy on an autonomous mobile robot controlled by 3-D coordinates that is obtained by a real-time indoor positioning system with spread spectrum (SS) ultrasonic signals communicated by code-division multiple access. Although many positioning systems have been investigated, the positioning system with the SS ultrasonic signals can measure identified multiple 3-D positions in every 70 ms with noise tolerance and error within 100 mm. This system is also robust to occlusion and environmental changes. However, thus far, the positioning errors in an autonomous mobile robot, controlled by these systems using the SS ultrasonic signals, have not been evaluated as an experimental study. Therefore, a positioning experiment for trajectory control is conducted using an autonomous mobile robot and our positioning system. The effectiveness of this positioning method for robot self-localization is shown, from this experiment, because the average control error between the target position and the robot's position at 29 mm is obtained.

• Journal of the Korea Safety Management & Science
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• v.17 no.2
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• pp.117-127
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• 2015

This study investigated the smoke blocking and control systems for the safety of residents evacuation and for the prevention of smoke spread through the central corridor in the event of central corridor type of intelligent building fire. We offered additional ways of utilizing smoke ventilators and intake ventilation equipment and utilized CFD-based fire simulation program(FDS Ver.5.5.3) in order to analyze the effect. As a result, many differences in the smoke block effect, depending on the application of smoke ventilator and location of installation, was found. In addition, the result was found that larger effect was showed not in the case of application of smoke ventilator in central corridor only but application in fire room. The reason is that the smoke leakage is blocked primarily as air is flowed in the fire room through open door by operation of intake smoke ventilator in the public corridor and secondarily, the smoke leakage to the public corridor could be blocked as fire and smoke were released to the opened smoke ventilator continuously. Especially, the effect was maximized through complex interactions by applying smoke ventilator and intake ventilation equipment in corridor together rather than applying smoke ventilator and intake ventilation equipment independently. The proposed measure through this study shall be considered from architectural plan as one of ways for blocking from smoke spread to the central corridor in the central corridor type of intelligent building. In addition, flaws on regulation shall be established and supplemented.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.6
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• pp.48-55
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• 2009

The feedback interference channels are those made through the multipaths that are built by moving and stationary objects around transmit and receive antennas mounted at the same point. This paper describes the method to measure the feedback interference channels in the rural regions and sides of highways and the analysis on channel characteristic parameters. Using the measured samples, we estimated scattering functions, delay power spectra, and Doppler power spectra, and we analyzed the channels using eight parameters including coherence bandwidth, coherence time, maximum excess delay, average excess delay, rms delay spread, Doppler shift, Doppler spread, and spread factor, and delay and Doppler cumulative distributions. Even though many observations are made, note that the feedback signals of high Doppler frequencies and large energy are observed in the sides of highways due to high speed vehicles while low Doppler frequencies occurred in the rural region due to rare traffic.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.2
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• pp.380-385
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• 2006

In this paper, a program that can be utilized to measure and analyze radio propagation characteristics is developed. This program is able to control the measurement instruments including spectrum analyzer through GPIB interface and analyze the measured data to yield mean excess delay and RMS delay spread. The measured path loss can be compared with theoretical value in free space or inside a tunnel. The measured and analyzed results can also be presented in the forms of graphs. As these tasks can be conducted on the spot of the measurements, this program is very helpful in performing and verifying the measurements immediately. In this thesis radio propagation characteristics with frequency bands of 2.45 and 5.8GHz in subway tunnels are measured by using the program. Path loss and delay spread in subway tunnel is measured and compared according to the form of antenna beam and LOS(Line of Sight) and N-LOS(Non-Line of Sight).

• The Journal of Asian Finance, Economics and Business
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• v.8 no.3
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• pp.171-179
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• 2021

In the international markets, financial variables can be volatile and may affect each other, especially in the crisis times. COVID-19, which began in China in 2019 and spread to many countries of the world, created a crisis not only in the global health system but also in the international financial markets and economy. The purpose of this study is to analyze the contagious effect of the COVID-19 pandemic on the volatility of selected financial variables such as Bitcoin, gold, oil price, and exchange rates and the connections between the volatilities of these variables during the pandemic. For this aim, we use the ARMA-EGARCH model to measure the impact of volatility and shocks. In other words, it is aimed to measure whether the impact of the shock on the financial variables of the contagiousness of the epidemic is also transmitted to the markets. The data was collected from secondary and daily data from September 2th 2019 to December 20th, 2020. It can be said that the findings obtained have statistically significant effects on the conditional variability of the variables. Therefore, there are findings that the shocks in the market are contaminated with each other.

• Journal of the Korean Society of Industry Convergence
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• v.24 no.6_2
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• pp.795-800
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• 2021

Magnesium fires require early fire extinguishment due to impulsive and rapid-fire expansion that makes difficult fire fighting. For this reason, efficient early fire fighting and appropriate prevention of fire spread are considered mainly as significant fire extinction measures. However, there is a limit to developing tools for metal fire fighting, such as devices, facilities, and fire extinguishing agents, due to a lack of regulatory instruments in South Korea. It often generates challenges to early fire fighting implementation by fire responders. Thus, the aim of this study is to investigate a measure for securing the efficiency of early fire fighting in magnesium. This study identified the applicability of the metal fire extinguisher used in the United States for magnesium fire through a performance test of a fire extinguishing agent for metal fire. Moreover, we implemented a free burning experiment using magnesium powder to compare varying combustion and extinction process that could occur during applying metal fire extinguishers. Finally, this study suggests measures of the use and application of metal fire extinguishers for magnesium.

• Journal of Korea Multimedia Society
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• v.17 no.7
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• pp.886-894
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• 2014

Recently, domestic animal disease caused tremendous damage to farmhouses and the damage stretched in nationwide with the spread of epidemic disease. To prevent animal diseases from happening again, the system development to easily measure the temperature of sick animals and identify of them is needed, thereby quickly treat them, reducing losses of farmhouses. However, a lack of related equipment and human resource hampered its effort to minimize its losses. This study tries to develop diagnosis system as part of measures to curb these domestic animal diseases. This paper present the 센서 node based on IEEE 802.15.4 which can be attached to the animal body for real-time temperature measurement. We design and implement tiny chip-type that can be attached to the body of animals. Then, we use available power only when measuring temperatures in a long term-basis. In this paper, the 센서 node was applied to horse's neck. We measure the horse's body temperature between $32.2^{\circ}C{\sim}33.7^{\circ}C$ and analyze phenomenon data for 4 months.

• Fire Science and Engineering
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• v.29 no.3
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• pp.1-5
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• 2015

The productivity and demand of porous material has been increasing by development of industry and increasing income. In particular, the fire caused by using wood flour risks wood processing industry and stock farm. The heat transfer of wood flour is carried into the depth direction by effect of oxidizer around flame, flame sometimes is progressed as smoldering. In the case of progressing as combustion fire, identifying the location of fire is difficult, and it leads to failing fire aid fire fighting. Therefore potential cause is acted as raising additional damage. This paper conducts experiments of downward deep seated fire of natural convection conditions. The samples is New Zealand wood flour that is demanded much in the domestic and oversea market. In this experiment, temperature of deep seated side is measure by changing wood flour density in holder The densities used in experiment are 3%, 5%, 10%, 15%. As a result, the tendency of temperature inside decreases as wood flour density increases. But, in the case of density which is above $0.2140g/cm^3$, the phenomenon, decreasing temperature, is not shown. The result of measurement show that average flame spread speed of wood flour is 0.249 mm/min.

• The Journal of Korean Society for Radiation Therapy
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• v.26 no.2
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• pp.183-189
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• 2014

Purpose : Intravenous contrast medium is a substance used to enhance the contrast of normal tissues or malignant tissues within the body. For this reason, intravenous contrast media have been extensively used form treatment-planning CT. However, when the patient is receiving proton therapy, there is no contrast medium in that moment. In this study, evaluate the influence of intravenous contrast medium on proton range and Spread-Out Bragg peak(SOBP) in Treatment Planning System(TPS). Materials and Methods : Hounsfield Unit(HU) value were measured by 20 liver cancer patients with phase change. and evaluate the proton range and SOBP on 5 liver proton treatment plan. By using the hand made water phantom measure the proton range and SOBP on proton treatment plan with changing HU and Depth. Results : Changing value(Pre contrast, Arterial phase, Portal phase) in liver cancer patient were ($58{\pm}5.7$, $75{\pm}9.5$, $117{\pm}14.6$ for liver tissue) and ($40{\pm}6.1$, $279{\pm}49.0$, $154{\pm}22.8$ for aorta), respectively. The mean difference of range was 2.5mm and SOBP was 1.4mm according to HU change. In phantom study, proton range was shorter and SOBP was narrowed with increasing HU. Conclusion : We verify that HU change lead to range and SOBP change in TPS. Additional study is required to verify that change of HU make range and SOBP be changed in actual substance.