• Journal of Korea Water Resources Association
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• 제32권6호
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• pp.637-647
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• 1999

This study investigated the applicability of generalized TOPMODEL approach which introduces the power law of decreasing transimissivity with depth instead of the traditional exponential decreasing function. The 50m digital elevation model(DEM) of Dongkog subwatershed at Wichon Test Watershed was used to perform runoff simulation. Random number generation algorithm was integrated into the calibration process for the reliable of model performance. General power law version of TOPMODEL with exponent 2 and 3 showed higher simulation efficiency than other the approaches. This results from the fact that the power law models with exponent 2 and 3 can represent the soil characteristics of study area better than other models.

• Journal of Applied Biological Chemistry
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• 제48권1호
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• pp.11-15
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• 2005

Salinity of soils in greenhouse has been increased by massive application of fertilizers. Nitrogen fertilizer was most popular, and thus nitrate became the majority of soil salinity. Accumulation of nitrate led to deleterious effects on the growth and development of crops and vegetables. Microbial strains able to utilize nitrate and thus remove excess nitrate from farm land soils were isolated from 15 different soils of greenhouses and plastic film houses. Four strains able to grow in medium containing 50 mM $KNO_3$ were isolated, among which only E0461 showed high capacity of nitrate uptake. Nitrate uptake by E0461 was dependent on culture medium and was increased by addition of tryptone and peptone. Although E0461 was able to grow without tryptone and peptone, growth was slow, and no nitrate uptake was observed. Nitrate appeared to facilitate E0461 growth in the presence of tryptone and peptone. Through kinetic analysis, nitrate uptake was measured at various concentrations of nitrate, and half-life was calculated. Nitrate concentration decreased with increasing incubation period, and plot between half-lives and initial concentrations of nitrate fitted to single exponential function. These results suggest one major factor plays an important role in microbial nitrate uptake.

• Journal of the Korean Institute of Intelligent Systems
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• 제14권5호
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• pp.571-576
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• 2004

This paper presents a delay dependent fuzzy $H_{\infty}$ controller design method for delayed fuzzy dynamic systems. Using delay-dependent Lyapunov function, the global exponential stability and $H_{\infty}$ performance problem arc discussed. A sufficient conditions for the existence of fuzzy controller is presented in terms of linear matrix inequalities(LMIs). A simulation example is given to illustrate the design procedures and performances of the proposed methods.

• Communications of the Korean Mathematical Society
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• 제17권3호
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• pp.535-540
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• 2002

Let X$_1$, X$_2$‥‥,X$\_$n/ be n independent and identically distributed random variables with continuous cumulative distribution function F(x). Let us rearrange the X's in the increasing order X$\_$1:n/ $\leq$ X$\_$2:n/ $\leq$ ‥‥ $\leq$ X$\_$n:n/. We call X$\_$k:n/ the k-th order statistic. Then X$\_$n:n/ - X$\_$n-1:n/ and X$\_$n-1:n/ are independent if and only if f(x) = 1-e(equation omitted) with some c > 0. And X$\_$j/ is an upper record value of this sequence lf X$\_$j/ > max(X$_1$, X$_2$,¨¨ ,X$\_$j-1/). We define u(n) = min(j|j > u(n-1),X$\_$j/ > X$\_$u(n-1)/, n $\geq$ 2) with u(1) = 1. Then F(x) = 1 - e(equation omitted), x > 0 if and only if E[X$\_$u(n+3)/ - X$\_$u(n)/ | X$\_$u(m)/ = y] = 3c, or E[X$\_$u(n+4)/ - X$\_$u(n)/|X$\_$u(m)/ = y] = 4c, n m+1.

• Journal of the Korea Institute of Information and Communication Engineering
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• 제17권8호
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• pp.1891-1898
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• 2013

To efficiently execute 3D graphic APIs, such as OpenGL and Direct3D, special purpose arithmetic unit(SFU) which supports floating-point sine, cosine, reciprocal, inverse square root, base-two exponential, and logarithmic operations is designed. The SFU uses second order minimax approximation method and lookup table method to satisfy both error less than 2 ulp(unit in the last place) and high speed operation. The designed circuit has about 2.3-ns delay time under 65nm CMOS standard cell library and consists of about 23,300 gates. Due to its maximum performance of 400 MFLOPS and high accuracy, it can be efficiently applicable to mobile 3D graphics application.

• Journal of the Korean Vacuum Society
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• 제21권5호
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• pp.258-263
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• 2012

Fe-diluted Si alloys grown on p-type Si (100) substrates by pulsed-laser deposition method were studied for structural, electrical, and magnetic properties. The X-ray diffraction patterns for these alloy samples showed a few of peaks with cubic structures such as FeSi, $Fe_3Si$, and $Fe_4Si$. The Fe-composition in alloys are confirmed as Fe atomic percent about 1.25~6.49 % from energy dispersive spectroscopy measurement. The resistivity as a function of the reciprocal temperature was indicated an exponential increase with two activation energies of 5.21 and 7.79 meV. The maximum value of the magnetization at 10 K was about 100 emu/cc, and the ferromagnetism was also observed until 350 K from total magnetization as a function of temperature with applied magnetic field of 3,000 Oe.

• Proceedings of the Korean Geotechical Society Conference
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• 한국지반공학회 2006년도 춘계 학술발표회 논문집
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• pp.414-423
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• 2006

Many construction projects adopt grouting technology to prevent the leakage of groundwater or to improve the shear strength of the ground. Recognition as a feasible field procedure dates back to 1925, Since then, developments and field use have increased rapidly. According to improvement of grout materials, theoretical study on grout penetration characteristics is demanded. Fluid of grout always tends to flow from higher hydraulic potential to lower and the motion of grout is also a function of formation permeability. Viscosity of grout is changed by chemical action while grout moves through pores. Due to the increment of viscosity, permeability is decreased. Permeability is also reduced by grout particle deposits to the soil aggregates. In this thesis, characteristics of new cement grout material that is developed recently is studied: injectable volume of new grout material is tested in two different sizes of sands, and the method to calculate injectable volume of grout is suggested with consideration of change in viscosity and clogging phenomena. The calculated values are compared with injection test results. Viscosity of new grout material is found to be an exponential function of time. And lumped parameter $\theta$ of new grout material to be used for assessing deposition characteristics is estimated by comparing deposit theory with injection test results considering different soil types and different injection pressure.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• 제15권6호
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• pp.492-505
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• 2022

This study is a study on the results of improving the logic to effectively transmit and decode compressed data in real time by improving the encoding and decoding performance of BL-beta codes that can be used for lossless real-time transmission of IoT sensing data. The encoding process of BL-beta code includes log function, exponential function, division and square root operation, etc., which have relatively high computational burden. To improve them, using bit operation, binary number pattern analysis, and initial value setting of Newton-Raphson method using bit pattern, a new regularity that can quickly encode and decode data into BL-beta code was discovered, and by applying this, the encoding speed of the algorithm was improved by an average of 24.8% and the decoding speed by an average of 5.3% compared to previous study.

• Journal of the Korea Institute of Information and Communication Engineering
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• 제13권4호
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• pp.727-736
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• 2009

In this paper, the $arccos(cos^{-1})$ arithmetic unit for mobile graphics accelerator is designed. The mobile vector graphics applications need tight area, execution time, power dissipation, and accuracy constraints compared to desktop PC applications. The designed processor adopts 2nd-order polynomial approximation scheme based on IEEE floating point data format to satisfy speed and accuracy conditions and reduces area via hardware sharing structure. The arccosine processor consists of 15,280 gates and its estimated operating frequency is about 125Mhz at operating condition of $0.35{\mu}m$ CMOS technology. Because the processor can execute arccosine function within 7 clock cycles, it has about 17 MOPS(million arccos operations per second) execution rate and can be applicable to mobile OpenVG processor. And because of its flexible architecture, it can be applicable to the various transcendental functions such as exponential, trigonometric and logarithmic functions via replacement of ROM and minor hardware modification.

• Journal of Sensor Science and Technology
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• 제4권4호
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• pp.10-15
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• 1995

Organic thin film electroluminescent(EL) cells were fabricated. Their output characteristics and luminance versus voltage characteristics were measured with different work function metal electrodes. The EL structure was Indium-Tin-Oxide(ITO)/hole transport layer/emission layer(electron transport layer)/metal electrode. PMMA+TPD(0.5 wt%), MC homopolymer+TPD(0.005 wt%) and (MC/MMA) copolymer+TPD(0.005 wt%) were used as hole transport layer. Ca, Mg, Mg:Ag(10:l) and Al were used as metal electrode. I-V output showed exponential feature, and the threshold voltage of 5 volts and the luminance of over 700 $Cd/m^{2}$ at 10 volts were observed.