• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.722-725
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• 2003

In AC plasma display, it is very important to quantify the wall voltage induced by the wall charge accumulated on the dielectric surface. If we know the quantities of the wall voltage in each period of every sequence; reset period, address period and sustain period, then it helps us to design the optimal driving waveform for high efficiency plasma display. We develop a new method to measure the wall voltage with VDS (Versatile Driving Simulator) system. From this method the wall voltage induced by a wall charge profiles just after the reset discharge of every cells in plasma display panel can be investigated and analyzed successfully. It is noted that the wall voltage profiles are influenced by the space charge and then they are stabilized as time goes by. It is also noted that both the remaining wall charge at the previous sequence and space charges contribute to wall voltage quantities just after the reset discharge. It is noted that the wall charges contribute dominantly after a few hundreds microseconds, while the space charges have been decayed within 100 ${\mu}s$ just after the reset discharge.

• Journal of Drive and Control
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• v.21 no.3
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• pp.46-55
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• 2024

In the agricultural machinery field, load analysis is mostly done through field tests. However, field tests are time-consuming and costly. There are also limitations in test conditions due to weather conditions. To overcome these environmental limitations, research on load analysis through simulation in a virtual environment is actively being conducted. This study aimed to select the most appropriate soil particle size for modeling by analyzing the effect of soil particle size on the prediction of draft force of the implement using simulation and soil particle modeling in a virtual environment with the discrete element method (DEM) software. The accuracy was verified by simulating the draft force for the same moving speed by soil particle size. For soil particle modeling, DEM soil modeling was performed by designing soil property measurement procedure. Soil particle correction was performed with a virtual vane shear test. Average DEM simulation results showed an error of 27.39% (19.43~40.66%) compared to actual measured data. The possibility of improvement was confirmed through additional research. Results of this study provide useful information for selecting soil particle size in soil modeling using DEM from the perspective of agricultural machinery research.

• Polymer(Korea)
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• v.28 no.1
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• pp.18-23
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• 2004

Superabsorbent poly(potassium acrylate-co-acrylamide)s were synthesized in particle form using inverse suspension polymerization technique. Mean diameter of the prepared polymer particles decreased from 300 to 50 $\mu\textrm{m}$ with increasing surfactant concentration. The dynamic and equilibrium swelling behaviors during water absorption and drying process were investigated by weight measurement. The swelling ratio of polymer particles in water changed according to not only polymer crosslinking density, but particle size, saline concentration of aqueous medium, and copolymer compositions. Water sorption amount was increased with decreasing particle size, crosslinking agent concentration, and ion concentration in bulk solution. Being different from the water sorption process, the drying process was not significantly affected by particle size, polymer composition, or crosslinking amount.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.268-275
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• 2006

Excavation works of cylindrical shafts and tunnels for the construction of a variety of infrastructures have been frequently going on in the urban areas. When ground excavations of cylindrical shafts and shallow tunnels proceed in the ground condition of high water level and silt particle component, ground water drawdown involving soil particle migration causes loosening of ground around tunnels and shafts, causes settlement and deformation of ground. Damages due to ground sinking and differential settlement can occur in the adjacent ground and structures. The extent and possibility of damage relevant to ground water drawdown and soil particle migration can't be so precisely expected in advance that we will face terrible damages in case of minor carefulness. This paper introduces two examples of construction management where using incremental deformation graph of inclinometer, we noticed the possibility of soil migration due to ground water drawdown in the excavation process of vertical shaft and shallow tunnel, analysed a series of measurement data in coupled connection, properly prepared countermeasures, so came into safe and successful completion of excavation work without terrible damages. The effort of this article aims to improve and develop the technique of design and construction in the coming projects having similar ground condition and supporting method.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.10
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• pp.78-85
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• 2004

The particle amount monitoring technique using ultrasound is proposed to determine the proper maintenance time of the filter in the supply process of pure gas in the unit of oxygen plant. There are advantages that it is adaptable in high temperature and high pressure, and it is not disturbed by being exposed in the gas flow, and it can be implemented very economically. The applicability of the ultrasonic technique is pre-studied through the theoretical analysis for the dependency of attenuation of ultrasonic wave on the particles in the gas flow. For the purpose, absorption, scattering and dispersion models are considered, and the attenuation by absorption and the change rate of the propagation speed are calculated fur the specific range of particle size and the ultrasonic wave frequency. It was expected by simulation that the absorptive attenuation by particles was the most sensitive to the change of particle amount. The experimental result showed high correspondence with the theoretical expectation so that this ultrasound attenuation measurement was proved to be highly effective for monitoring the amount of floating particles in the gas flow.

• Journal of Fisheries and Marine Sciences Education
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• v.28 no.3
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• pp.831-840
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• 2016

Hydrodynamic condition can be used to predict particle movement within water column and the results used to optimize environmental conditions for effective site selection, setting of environmental quality standard, waste dispersion, and pathogen transfer. To predict the extent of movement of particle from land, 3D hydrodynamic model that includes particle tracking module was applied to Geoje Bay and to calibrate particle tracking model, floating buoy measurement is operated. The model results show that short time is required for particles released into system from river to be transported to the shellfish farming area. It takes about 2 days for the particles to shellfish farming area under mean flow condition. It meant Geoje Bay, especially shellfish farming area is vulnerable to anthropogenic waste from river.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.194-194
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• 2011

The effects of argon neutral beam (NB) energy on the amorphous carbon (a-C) films were investigated, while the a-C films were deposited by neutral particle beam assisted sputtering (NBAS) system. The energy of neutral particle beam can be controlled by reflector bias voltage directly as a unique operating parameter in this system. The deposition characteristics of the films investigated of Raman spectra, UV-visible spectroscopy, electrical conductivity, stress measurement system, and ellipsometer indicate the properties of amorphous carbon films can be manipulated by only NB energy (or reflector bias voltage) without changing any other process parameters. We report the effect of reflector bias voltage in the range from 0 to -1KV. By the increase of the reflector bias voltage, the amount of cross-linked sp2 clusters as well as the sp3 bonding in the a-C film coated by the NBAS system can be increased effectively and the composition of carbon thin films can be changed from nano-crystalline graphite phase to amorphous carbon phase.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.216-219
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• 2002

Much quantity of anti-tracking agent, ATH is added to the silicone rubber for the protection of silicone rubber against surface discharge. Hydrophobicity recovery properties of silicone rubber could be different by the content, surface treatment state and particle size of ATH. Because hydrophobicity of silicone rubber is depend much on the surface state of ATH. In this paper, the properties of silicone rubber is investigated according to the addition of different particle size of ATH to the silicone rubber. Hydrophobicity recovery properties and arc resistance of silicone rubber were investigated according to the addition of different particle size of ATH. Hydrophobicity recovery properties of silicone rubber were evaluated by the measurement of contact angle.

• Particle and aerosol research
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• v.10 no.4
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• pp.163-167
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• 2014

Particle number portable emission measurement system (PN-PEMS) is an instrument for measuring number concentration of automobile exhaust. The principle of some pre-existing commercial PN-PEMS is to charge particles and display the number of particles by measuring current. However, this method has some problems for measuring exhaust. In this study, to solve these issues, we have developed a single particle counting PN-PEMS based condensation particle counter (CPC). The PN-PEMS based CPC does not affect driving conditions and it is convenient for mobile because the instrument is small and light in structure. We evaluated counting efficiency of PN-PEMS based CPC by using electrostatic method (electrometer and Faraday cup).

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.157-163
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• 2011

Combustion of magnesium dust particle were fabricated test devices and combustion experiments were carried out. The ignition delay time were measured in change of magnesium particle mass flow rate in premixed flame. According to increasing magnesium particle mass flow rate, ignition delay time were more shorter. In addition, magnesium dust combustion temperature were measured different particle sizes and o/f ratio by two wavelength pyrometry. Dust combustion flame temperature is almost similarly, through to equivalence ratio, confirm the combustion flame temperature range characteristics.