• Korean journal of communication and information
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• v.54
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• pp.98-117
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• 2011

This paper is a theoretical inquiry of the changing roles of digital technologies in the representation of risk. Critically examining existing perspectives on risk society and risk communication, this paper argues that digital technologies and images in risk communication have been relatively understudied. Having said that, this paper suggests that Actor-network Theory provide useful theoretical tools for current studies on how digital technologies affect contemporary risk communication practices. Furthermore, this paper examines varied recent studies investigating how digital technologies of visualization are at play in risk communication practices. In doing so, this paper demonstrates how digital images and technologies interrupt the processes that scientific evidence is presented and facts are constructed in varied contemporary scientific reasoning. It will focus on the emerging mode of seeing and visual regime made possible by the increased usage of digital image and technologies, which are characterized by networked connection, sensor, computerized algorithm, and increased storage space. Finally this paper will discuss on the implications on future studies on the roles of digital images and technologies in risk communication practices in Korean context.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.6
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• pp.68-75
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• 2011

A vehicle fuel economy is very important issue in view of fuel cost and environmental regulation. It has been improved according to the performance improvement of the vehicle engine, power train and many components. It was evaluated at given mode (LA-4, FTP-75, etc) on an engine dynamometer or computer simulation program. In this paper, the fuel economy improvement cruise control algorithms as controling a vehicle velocity by road load calculated and predicted in a real expressway with gradient was studied. Firstly, the altitude and distance data which was measured with GPS sensor was already installed in the ECU of a vehicle. Then the vehicle equipped with GPS receiver is driven the same expressway. The ECU calculates the gradient angle and the in-/decreasing velocity using the gradient angle by comparing the current received distance and altitude data from GPS with the saved data ahead of the vehicle. Therefore the ECU can calculate and predict the vehicle velocity considering tolerance velocity of next position with running. Then the ECU controls the vehicle velocity to meet this predicted velocity in all section. Three cruise control algorithms with the different velocity profiles for the improvement of fuel economy are proposed and compared with the computer simulation results that the vehicle runs on Youngdong expressway. The proposed CVELCONT2 and CVELCONT3 algorithms were improved 3.7% and 4.8% of fuel economy compared with CONSTVEL which is steady cruising algorithm. These two algorithms are recommended as the Eco-cruise drive methodologies in this paper.

• Progress in Superconductivity and Cryogenics
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• v.16 no.4
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• pp.44-48
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• 2014

A liquid nitrogen-cooled prepolarization ($B_p$) coil made for ultra-low field nuclear magnetic resonance and magnetic resonance imaging (ULF-MR) designed to generate 7 mT/A was fabricated. However, with suspected internal insulation failure, the coil was investigated in order to find out the source of the failure. This paper reports detailed build of the failed $B_p$ coil and a number of analysis methods utilized to figure out the source and the mode of failure. The analysis revealed that pyrolytic graphite sheet linings put on either sides of the coil for better thermal conduction acted as an electrical bridge between inner and outer layers of the coil to short out the coil whenever a moderately high voltage was applied across the coil. A simple model circuit simulation corroborated the analysis and further revealed that the failed insulation acted effectively as a damping resistor of $R_{d,eff}=6{\Omega}$ across the coil. This damping resistance produced a 50 ms-long voltage tail after the coil current was ramped down, making the coil not suitable for use in ULF-MR, which requires complete removal of magnetic field from $B_p$ coil within milliseconds.

• Advances in aircraft and spacecraft science
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• v.5 no.2
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• pp.225-237
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• 2018

The difficulties of satellite vibration testing are due to the commonly expressed qualification requirements being incompatible with the limited performance of the entire controlled system (satellite + interface + shaker + controller). Two features cause the problem: firstly, the main satellite modes (i.e., the first structural mode and the high and low tank modes) are very weakly damped; secondly, the controller is just too basic to achieve the expected performance in such cases. The combination of these two issues results in oscillations around the notching levels and high amplitude beating immediately after the mode. The beating overshoots are a major risk source because they can result in the test being aborted if the qualification upper limit is exceeded. Although the abort is, in itself, a safety measure protecting the tested satellite, it increases the risk of structural fatigue, firstly because the abort threshold has been already reached, and secondly, because the test must restart at the same close-resonance frequency and remain there until the qualification level is reached and the sweep frequency can continue. The beat minimum relates only to small successive frequency ranges in which the qualification level is not reached. Although they are less problematic because they do not cause an inadvertent test shutdown, such situations inevitably result in waiver requests from the client. A controlled-system analysis indicates an operating principle that cannot provide sufficient stability: the drive calculation (which controls the process) simply multiplies the frequency reference (usually called cola) and a function of the following setpoint, the ratio between the amplitude already reached and the previous setpoint, and the compression factor. This function value changes at each cola interval, but it never takes into account the sensor signal phase. Because of these limitations, we firstly examined whether it was possible to empirically determine, using a series of tests with a very simple dummy, a controller setting process that significantly improves the results. As the attempt failed, we have performed simulations seeking an optimum adjustment by finding the Least Mean Square of the difference between the reference and response signal. The simulations showed a significant improvement during the notch beat and a small reduction in the beat amplitude. However, the small improvement in this process was not useful because it highlighted the need to change the reference at each cola interval, sometimes with instructions almost twice the qualification level. Another uncertainty regarding the consequences of such an approach involves the impact of differences between the estimated model (used in the simulation) and the actual system. As limitations in the current controller were identified in different approaches, we considered the feasibility of a new controller that takes into account an estimated single-input multi-output (SIMO) model. Its parameters were estimated from a very low-level throughput. Against this backdrop, we analyzed the feasibility of an LQG control in cancelling beating, and this article highlights the relevance of such an approach.

• Analytical Science and Technology
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• v.19 no.6
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• pp.482-489
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• 2006

Two electrode-based lactate biosensor was prepared by immobilizing lactate oxidase (LOD) obtained from pediococcus species in a poly(vinyl alcohol). Hydrogen peroxide ($H_2O_2$) produced by the reaction of lactate and LOD was detected on the Pt-black that was electrochemically deposited on the Au electrode. Sensors fabricated with Pt-black deposited Au electrode provided a high current of $H_2O_2$ oxidation at a substantially lowered applied potential (+300 mV vs. Ag/AgCl), resulting in reduced interferences from easily oxidizable species such as ascorbic acid, acetaminophen, and uric acid. An outer membrane is formulated by adjusting water uptake of hydrophilic polyurethane (HPU). The sensor performance was evaluated in vitro with both flow-through arrangement and static mode. The sensor showed a linear range from 0.1 mM to about 9.0 mM in 0.05 M phosphate buffer (pH 7.6) containing 0.05 M NaCl. Storing the sensors prepared in this work at $4^{\circ}C$ buffer solution while not in use, they provided same electrochemical performance for more than 25 days.

• Journal of the Korea Society of Computer and Information
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• v.14 no.2
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• pp.157-168
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• 2009

In this paper, a photovoltaic system is designed with a step up chopper and single phase PWM(Pulse Width Modulation) voltage source inverter. Where proposed Synchronous signal and control signal was processed by one-chip microprocessor for stable modulation. The step up chopper operates in continuous mode by adjusting the duty ratio so that the photovoltaic system tracks the maximum power point of solar cell without any influence on the variation of insolation and temperature because solar cell has typical voltage and current dropping character. The single phase PWM voltage source the inverter using inverter consists of complex type of electric power converter to compensate for the defect, that is, solar cell cannot be developed continuously by connecting with the source of electric power for ordinary use. It can cause the effect of saving electric power. from 10 to 20[%]. The single phase PWM voltage source inverter operates in situation that its output voltage is in same phase with the utility voltage. In order to enhance the efficiency of photovoltaic cells, photovoltaic positioning system using sensor and microprocessor was design so that the fixed type of photovoltaic cells and photovoltaic positioning system were compared. In result, photovoltaic positioning system can improved 5% than fixed type of photovoltaic cells. In addition, I connected extra power to the system through operating the system voltage and inverter power in a synchronized way by extracting the system voltage so that the phase of the system and the phase of single-phase inverter of PWM voltage type can be synchronized. And, It controlled in order to provide stable pier to the load and the system through maintaining high lurer factor and low output power of harmonics.

• Atmosphere
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• v.12 no.4
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• pp.20-42
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• 2002

Based on the "Mid to Long Term Plan for Space Development", a project to launch COMeS (Communication, Oceanography, and Meteorological Satellite) into the geostationary orbit is undergoing. Accordingly, KMA (Korea Meteorological Administration) has defined the meteorological missions and prepared the user requirements to fulfill the missions. To make a realistic user requirements, we prepared a first draft based on the ideal meteorological products derivable from a geostationary platform and sent the RFI (request for information) to the sensor manufacturers. Based on the responses to the RFI and other considerations, we revised the user requirement to be a realistic plan for the 2008 launch of the satellite. This manuscript introduces the revised user requirements briefly. The major mission defined in the revised user requirement is the augmentation of the detection and prediction ability of the severe weather phenomena, especially around the Korean Peninsula. The required payload is an enhanced Imager, which includes the major observation channels of the current geostationary sounder. To derive the required meteorological products from the Imager, at least 12 channels are required with the optimum of 16 channels. The minimum 12 channels are 6 wavelength bands used for current geostationary satellite, and additional channels in two visible bands, a near infrared band, two water vapor bands and one ozone absorption band. From these enhanced channel observation, we are going to derive and utilize the information of water vapor, stability index, wind field, and analysis of special weather phenomena such as the yellow sand event in addition to the standard derived products from the current geostationary Imager data. For a better temporal coverage, the Imager is required to acquire the full disk data within 15 minutes and to have the rapid scan mode for the limited area coverage. The required thresholds of spatial resolutions are 1 km and 2 km for visible and infrared channels, respectively, while the target resolutions are 0.5 km and 1 km.