• Journal of the Korean Society for Precision Engineering
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• v.22 no.4
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• pp.181-187
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• 2005

In this study, a microchip system fabricated with MEMS technology was developed to detect bioelectrical signals. The developed microchip using the conductivity of gold nanoparticles could detect the biopotential with a high sensitivity. For designing the microchip, simulations were performed to understand the effects of the size and number of nanoparticles, and the sensing width between electrodes on the detection of biosignals. Then, a series of experiment was performed to validate the simulation results and understand the feasibility of the proposed microchip design. Both simulation and experimental results showed that as the sensing width between electrodes increased the conductivity decreased. Also, the conductivity increased as the density of gold nanoparticles increased. In addition, it was found that the conductivity that changes with the nanoparticles density could be approximated by a cumulative normal distribution function. The developed microchip system could effectively apply when a biosignals should be measured with a high sensitivity.

• Tribology and Lubricants
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• v.34 no.5
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• pp.175-182
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• 2018

Accumulation of coal ash at the boiler wall reduces combustion and fuel efficiency. The design of a wall blower is important to effectively remove coal ash. We present numerical results for the removal of coal ash from boiler walls of domestic coal-fired power plants, associated with the computational fluid dynamics for the flow from spray nozzle to boiler wall. The numerical model simulates an erosion process in which the multiphase fluid comprising saturated vapor and fluid water is sprayed from the nozzle, and the water particles impact the boiler wall. We adopt the Finnie erosion model for water particles. We obtain the erosion rate density as a function of nozzle angle and its injection angle. As excessive coal ash removal usually induces damage to the boiler wall, the removal operation typically focuses on a large area with uniform depth rather than the maximum removal of coal ash at a specific location. In order to estimate the removal performance of the wall blower nozzle considering several functionality and reliability factors, we evaluate the optimal injection and nozzle angles with respect to the biggest cumulative and highest erosion rates, as well as the widest range and lowest standard deviation of the erosion rate distribution.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.27 no.1
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• pp.39-47
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• 2005

The purpose of this study is to review the prognosis of the TG Osseotite implant(3i Co, USA) placed in partial edentulous area of oral cavity and to suspect the possible causes leading to failure. 124 TG Osseotite implants that had been inserted between 2000 - 2002 were followed up for 2 years(avg : 9.5 months) in function. Medical records, and radiographs were evaluated and analyzed by the over all success rate, gender and age factor, general disease, implant fixture length and diameter, implant site, bone density, and various surgical methods. Chi square test was used statistically. Of the 124 TG Osseotite implants, 9 implants(7.3%) were removed in early phase and 3 implants(2.4%) were in late phase. The cumulative survival rate was 90.2%. The failure of the TG Osseotite implant was closely related with the use of bone graft techniques such as sinus elevation or immediate implantation and not with the age, sex, general disease, implant site, bone density of implanted site. The failure of the TG Osseotite implant was well developed when it was the wide type of implant and it was inserted for single tooth replacement. The developement of peri-implantitis was the most important factor in the failure of the TG Osseotite implant.

• Journal of Korean Society on Water Environment
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• v.26 no.2
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• pp.243-251
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• 2010

Evapotranspiration and rainfall-runoff are the major components of hydrological cycle and thereby the changes of them can directly affect the wetness/dryness or runoff characteristics of basins. In this study the wetness/dryness in Geum river basin are classified by dint of cumulative probability density function of monthly moisture index and the long term changes of them are analyzed based on climatic water balance concept. The drought events in Geum river basin are selected through evaluation of monthly moisture index and the various hydrological properties of them are investigated in detail. Also the trends of time-series of climatic water balance components are examined by Seasonal Kendall test and the variability of hydrological cycle in Geum river basin during the recent decade is inquired. It is judged that the results of this study can be contributed to establishment of the counter plan against the future drought events as the fundamental information.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.517-520
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• 2005

In this paper, we propose a motion picture processor for CSTN-LCD without gamut problem. The proposed method employed CDF(Cumulative Density Function) in order to perform a mutual independent in image gradation and color balance. In addition, the proposed method has solved a gamut problem used by conversion of RGB system and CMY system. Also, we apply the BFI (Black Field Insertion) to the design to compensate for response time of a LC (Liquid Crystal). The proposed hardware architecture has been implemented and verified using a FPGA on prototype board. Visual test and standard deviation of histogram were introduced to evaluate the result of the proposed method and the original ones.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.448-451
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• 2005

This paper presents the methodology to analyze flow duration characteristics and performance prediction for small hydro power(SHP) plants and its application. The flow duration curvecan be decided by using monthly rainfall data at the most of the SHP sites with no useful hydrological data. It was proved that the monthly rainfall data can be characterized by using the cumulative density function of Weibull distribution and Thiessen method were adopted to decide flow duration curve at SHP plants. And, the performance prediction has been studied and development. One SHP plant was selected and performance characteristics was analyzed by using the developed technique. Primary design specfications such as design flowrate, plant capacity, operational rate and annual electricity production for the SHP plant were estimated. It was found that the methodology developed in this study can be a useful tool to predict the performance of SHP plants and candidate sites in Korea.

• Communications for Statistical Applications and Methods
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• v.18 no.4
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• pp.467-475
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• 2011

This paper develops the noninformative priors for the stress-strength reliability from one parameter generalized exponential distributions. When this reliability is a parameter of interest, we develop the first, second order matching priors, reference priors in its order of importance in parameters and Jeffreys' prior. We reveal that these probability matching priors are not the alternative coverage probability matching prior or a highest posterior density matching prior, a cumulative distribution function matching prior. In addition, we reveal that the one-at-a-time reference prior and Jeffreys' prior are actually a second order matching prior. We show that the proposed reference prior matches the target coverage probabilities in a frequentist sense through a simulation study and a provided example.

• Structural Engineering and Mechanics
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• v.38 no.4
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• pp.503-516
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• 2011

Uncertainty in concrete properties, including concrete modulus of elasticity and modulus of rupture, are predicted by developing a microstructural homogenization model. The homogenization model is developed by analyzing a concrete representative volume element (RVE) using the finite element (FE) method. The concrete RVE considers concrete as a three phase composite material including: cement paste, aggregate and interfacial transition zone (ITZ). The homogenization model allows for considering two sources of variability in concrete, randomly dispersed aggregates in the concrete matrix and uncertain mechanical properties of composite phases of concrete. Using the proposed homogenization technique, the uncertainty in concrete modulus of elasticity and modulus of rupture (described by numerical cumulative probability density function) are determined. Deflection uncertainty of reinforced concrete (RC) beams, propagated from uncertainties in concrete properties, is quantified using Monte Carlo (MC) simulation. Cracked plane frame analysis is used to account for tension stiffening in concrete. Concrete homogenization enables a unique opportunity to bridge the gap between concrete materials and structural modeling, which is necessary for realistic serviceability prediction.

• The KIPS Transactions:PartB
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• v.11B no.7 s.96
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• pp.779-784
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• 2004

In this paper, we have proposed an image contrast control method using brightness preserving on the FPD(Flat Panel Display). The proposed method can be easily applied to the FPD required real-time processing, since hardware complexity is greatly reduced using linear approximation method of CDF(Cumulative Density Function). For effective processing of the proposed algorithm, we have utilized the sample value of CDF and Barrel Shift. Visual test and standard deviation of their histogram have been introduced to evaluate the resultant output images of the pro-posed method and the original ones.

• Korean Journal of Hydrosciences
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• v.3
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• pp.81-96
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• 1992

This study represents the methodology for feasibility analysis of small hydro power SHP plant. Cumulative density function of Weibull distribution and Thiessen method were adopted to decide flow duration curve at SHP candidate site. The perfomance prediction model and construction cost estimation model for tunnel-type SHP plant were developed. Eight tunnel -type SHP candidate sites existing on Han-river were selected and surveyed for actual site reconnaissance. The performance characteristics and economical feasibility for these sites were analyzed by using developed models. As a result, it was found that the optimum design flowrate with the lowest unit generation cost for tunel-type SHP candidate site were the flowrate concerming with between 20% and 30% of time ratio on the flow duration curve. Additionally, primary design specifications such as design flowrate, effective head, capacity, annual averageload factor, annual electricity production were estimated and discussed for eight surveyed SHP candidate sites.