• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.6
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• pp.2369-2379
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• 2013

The Soil-Water Characteristics Curve (SWCC) is affected by the initial density of soil under unsaturated condition. Also, the characteristic of hydraulic conductivity is changed by the initial density of soil. To study the effect of initial density of unsaturated soil, SWCC and the Hydraulic Conductivity Function (HCF) of Jumoonjin sand with various relative densities, 40%, 60% and 75% were measured in both drying and wetting processes. As the results of SWCC estimated by van Genuchten (1980) model, the parameter related to Air Entry Value(AEV), ${\alpha}$ in the wetting process is larger than that in drying process, but the parameters related to the SWCC slope, n and the residual water content, m are larger than those in wetting process. The AEV is increased or Water Entry Value (WEV) is decreased with increasing the relative density of sand. The AEV is larger than the WEV at the same relative density of sand. As the results of HCF estimated by van Genuchten (1980) model which is one of the parameter estimation methods, the unsaturated hydraulic conductivity maintained at a saturated one in the low level of matric suctions and then suddenly decreased just before the AEV or the WEV. The saturated hydraulic conductivity in drying process is larger than that in wetting process. The saturated hydraulic conductivity is decreased with increasing the relative density of sand in both drying and wetting processes. Also, the hysteresis in unsaturated HCFs between drying and wetting process was occurred like the hysteresis in SWCCs. According to the test results, the AEV on SWCC is decreased and the saturated hydraulic conductivity is increased with increasing the initial density. It means that SWCC and HCF are affected by the initial density in the unsaturated soil.

• Journal of Soil and Groundwater Environment
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• v.8 no.3
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• pp.13-22
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• 2003

Laboratory scale study for an air injection and flowing aspect of groundwater saturated zone was conducted for three sediment grains (AMG 0.34, 1.38, 3.89 mm diameter). Air flow for AMG (Average Modal diameter Grains) 0.34 mm diameter grain size provides indication of pattern of channelized air flow in saturated zone and expansion state in above saturated zone. Maximum area of influence is approximately l5.2%/$\textrm{m}^2$for AMG of 0.34 mm diameter. For AMG of 1.38 mm and 3.89 mm modal diameter grains, air flow are pervasive air flow, forming a symmetrical cone of influence around the injection point. Maximum areas affected are 37%/$\textrm{m}^2$for AMG 1.38 mm diameter and 30%/$\textrm{m}^2$for AMG 3.89 mm diameter. AMG 1.38 mm and 3.89 mm diameter grains show onset of collapse and approach to steady state in above saturated zone, respectively. In this study, optimal sites for in situ air sparging, may be grain diameters between about AMG 1.5-2.5 mm diameter.

• Science of Emotion and Sensibility
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• v.9 no.1
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• pp.1-7
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• 2006

The purpose of this study is to analyze the effects of the inhalation of 30% oxygen on heart rate and oxygen saturation ($SPO_2$) during cycle isokinetic exercise, in comparison with the inhalation of 21% oxygen. This study used oxygen supply equipment that can supply each of 21% and 30% oxygen constantly at a rate of 8 liter/min. Ten healthy male college students ($25.2{\pm}2.2$ years) participated in the experiment twice, one for 21% oxygen and the other for 30% oxygen. Each experiment was composed of three sections (a total of 18 minutes), which were composure (2 minutes), cycle isokinetic exercise at a speed of $20{\pm}1km/h$ (10 minutes) and recovery (6 minutes). 21% or 30% oxygen was supplied only during the sections of isokinetic exercise and restoration. Heart rate during isokinetic exercise and recovery was lower with the inhalation of 30% oxygen than with that of 20% oxygen but no difference was observed in $SPO_2$. $SPO_2$ was not different possibly because the same work load was applied to the group of 21% oxygen and that of 30% oxygen. Heart rate was reduced with the inhalation of 30% oxygen possibly because a larger quantity of oxygen was supplied at the same work load.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.7
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• pp.1332-1340
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• 1992

A novel approach based on a nonlinear compensator is prposed to prevent 'windup', which is caused by the saturation of the acutator and the integral action of the controller. The anti-windup compensator is located between the conventional linear controller, designed neglecting the saturation, and the actuator. It was proven based on the describing function method that, if the closed loop control systems are stable assuming no saturation, then there may exist a range of compensator gain which prevents any limit-cycle. The computer simulation results show that the compensator proposed in the manuscript can eliminate the limit cycle and improve the transient response.

• ETRI Journal
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• v.14 no.1
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• pp.52-65
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• 1992

전자선 직접묘사 (E-beam direct writing lithography) 방법을 이용하여 $0.2\mum$ 과 $0.3\mum$ 의 게이트길이를 가지는 NMOS 트랜지스터를 제작하였다. 게이트만 전자선 직접묘사 방법으로 정의하고 나머지는 optical stepper를 이용하는 Mix & Match 방식을 사용하였다. 게이트산화막의 두께는 최소 6nm까지 성장시켰으며, 트랜지스터구조로서는 lightly-doped drain(LDD) 구조를 채택하였다. 짧은 채널효과 및 punch through를 줄이기 위한 방안으로 채널에 깊이 붕소이온을 주입하는 방법과 well을 고농도로 도핑하는 방법 및 소스와 드레인에 $p^-$halo를 이온주입하는 enhanced lightly-doped drain(ELDD) 방법을 적용하였으며, 제작후 성능을 각각 비교하였다. 제작된 $0.2\mum$의 게이트길이를 가지는 소자에서는 문턱전압과 subthreshold기울기는 각각 0.69V 및 88mV/dec. 이었으며, Vds=3.3V에서 측정한 포화 transconductance와 포화 드레인전류는 각각 200mS/mm, 0.6mA/$\mum$이었다. $0.3\mum$소자에서는 문턱전압과 subthreshold 기울기는 각각 0.72V 및 82mV/dec. 이었으며, Vds=3.3V에서 측정한 포화 transconductance는 184mS/mm이었다. 이러한 결과는 전원전압이 3.3V일 때 실제 ULSI에 적용가능함을 알 수 있다.

• Tunnel and Underground Space
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• v.21 no.2
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• pp.138-144
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• 2011

Mine closure does often accompany the flooding of mine galleries due to ceasing a pumping operation. When a mine gallery is flooded, rocks around the gallery are fully saturated and the gallery is subject to a water pressure. The uniaxial unconfined compressive strength of a rock depends on its water content and decreases as the water content increases. A water pressure may originate the crack growth of a rock or the discontinuity growth of rock mass. Although the water in a gallery will give some support pressure inside the gallery, the degradation of rock mass properties caused by a water pressure will reduce the stability of the gallery. In this study, 2-dimensional discontinuous and 3-dimensional continuous numerical analyses have been conducted to evaluate an effect that a reduction of rock mass properties around the gallery induced by a water pressure has on the stability of mine gallery. The numerical analyses show that a reduction of rock mass properties caused by a water pressure increases displacements of rock mass around mine gallery. 2-dimensional model is found to give larger values of displacement than 3-dimensional model.

• Korean journal of applied entomology
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• v.42 no.1
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• pp.9-13
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• 2003

Cuticular hydrocarbons of antenna, legs and wings from two species of honeybee worker of Apis mellifera L. and Apis cerana F. can be analyzed directly with gas chromatograph and GC/MS without solvent extraction. The saturated hydrocarbons identified in selected part of both species were nC22, nC23, nC25-nC3O, nC32 and nC34 except nC24. Two saturated hydrocarbons, nC26 (23.0-42.6%) and nC28 (16.8-54.8%), were major compounds in both species and others were minor compounds. A. mellifera can be distinguished from A. cerana F. by having higher proportion of nC30, nC32 and nC34 by having lower proportion of nC25 from three selected part of both species.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.2
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• pp.95-103
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• 2007

An analytical closed-form solution for wave propagation velocity and damping in saturated porous media is presented in this paper The fully coupled field model with compressible solid Brains and pore water were used to derive this solution. An engineering approach for the analysis of fully saturated porous media was adopted and closed-form solutions for one dimensional wave propagation in a homogeneous domain were derived. The solution is highly versatile in that it considers compression of the solid grains, compression of the pore water, deformation of the porous skeleton, and spatial damping and can be used to compute wavespeeds of first and second kind and damping coefficients in various geologic materials. This solution provides a means of analyzing the influence of material property variations on wavespeed and attenuation. In Part 2 of this work the theoretical solution is incorporated into the numerical code and the code is used in a parametric study on wave propagation velocity and damping.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.05a
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• pp.333-336
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• 2001

The transient response in PDFA(Praseodymium-Doped Fiber Amplifier) is theoretically investigated. The PDFA has the spectral gain band in 1.3${\mu}{\textrm}{m}$. The transient model includes the transient buildup of the population inversion, the pump power, and the signal power and their transient variation along the fiber amplifier. The numerical analysis of transient model can predict the gain saturation, the variation of pump power and the gain as a function of the fiber length. It also shows the gain saturation and recovery effects depending on the pumping rate lead to distortion and saturation in the amplification of optical pulse. The results of numerical analysis, for the case of the Pr ion concentration of 1000ppm and the pump power of 0.5W the gain saturation is obtained 30dB at the length of 5m and the saturation time of upper level is 250 $mutextrm{s}$.

• Journal of Conservation Science
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• v.28 no.1
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• pp.75-86
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• 2012

Iksan Mireuksaji Stone pagoda was built A.D. 639 when King Moo was governing Baekje, in which Sarira has been enshrined in a hole dug in the stereobate for 1,370 years. In South Korea, about 150 cases of Sarira have been found so far. In this connection, many studies have been conducted on how to manage it and on its genesis, but there have been no data on environments to which it has been exposed. In this study, accordingly, researches were made into environments to which Sarira has been exposed as well as into how much it has been damaged under the environments. Sarira in wooden pagodas was influenced greatly by water, but that in stone pagodas by saturated relative humidity. Thus, Sarira in the containers was significantly influenced by the outside temperature for 1 to 2 days, but had no any reaction to humidity. The time it took for the humidity in a Sarira container to reach its maximum, varied depending upon the humidity of the day when Sarira was enshrined. In the case of this pagoda, the humidity reached its maximum 30 days later.