• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.9 no.1
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• pp.33-40
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• 2011

In the compacted bentonite containing $Ag_2O$, the transport of iodide ion was investigated by Through-diffusion method. It is confirmed that Iodide ion is transported by diffusion process in the compacted bentonite containing $Ag_2O$ as well as in the compacted bentonite without $Ag_2O$. However, the lag-time of iodide ion in the compacted bentonite containing $Ag_2O$ is larger than that in the compacted bentonite without $Ag_2O$. The increase of the lag-time was observed in pure iodide ion solution and also in 0.1M NaCl-iodide ion solution. The apparent diffusion coefficient of iodide ion in the compacted bentonite containing $Ag_2O$ has lower value than that in the compacted bentonite without $Ag_2O$. The effect of $Ag_2O$ on the effective diffusion coefficient was not clearly investigated in the compacted bentonite containing $Ag_2O$ while the values of effective diffusion coefficient of iodide ion in the compacted bentonite without $Ag_2O$ obtained in this study were similar to those in the compacted bentonite reported in the literature.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 1999.06a
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• pp.51-59
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• 1999

산불발생 요인으로 캐나다와 미국의 경우에는 자연적인 현상이 대부분을 차지하고 있으나 우리나라의 경우에는 입산 자들의 부주의, 농산폐기물소각 등에서 오는 인위적인 원인들이 대부분을 차지하고 있다. 또한 산불발생시 즉시 진화하기 어려운 이유는 우리나라의 지형특성상 구릉지가 많아 발견되기 어렵고, 산불의 진압을 위한 장비와 인력동원에서 오는 지연시간 및 산불확산에 영향을 미치는 요인들의 변화를 예측하기 어렵다는 점에 있다. (중략)

• The Journal of the Acoustical Society of Korea
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• v.1 no.1
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• pp.27-36
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• 1982

본 논문에서는 종래의 디지털신호 처리 방식에 비해 소형이며 광대역폭 신호를 처리할 수 있는 AE 콘빌버가 스펙트럼 확산통신 방식에서 높은 신호처리 이득과 다이나믹 레인지를 갖는 프로그램이 가능한 정합필터로 사용 될 수 있음을 실험적으로 제시하였다. 본 실험에서 사용한 AE 콘벌버는 안전 재료인 YZ-LINbO\sub 3\ 위에 중심 주파수 50MHz, 대역폭 11MHz인 SAW 지연선을 제작하고 그 위 에 저항율 50 ohm-cm인 P형 실리콘을 장착하여 구성하였으며, 이 소자는 63? PN 코드로 변조된 P나 신호를 인가하여 신호처리이득이 18dB인 프로그램이 가능한 정합필터로 사용될 수 있음을 보였다.

• Information and Communications Magazine
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• v.32 no.9
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• pp.37-43
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• 2015

5세대(5G) 이동통신은 다양한 모바일 기기와 가입자의 확산에 따른 모바일 트래픽 증가를 수용할 뿐만 아니라 원격의료와 같이 저지연을 기반으로 하는 새로운 형태의 서비스를 제공함을 목표로 한다. 저지연 서비스는 수 밀리세컨드 (ms) 이내의 단대단 지연 요구사항을 가지며 무선 구간에서의 전송지연도 기존 시스템 대비 획기적인 단축을 필요로 한다. 본고에서는 5G 저지연 서비스의 개념 및 요구사항, 그리고 저지연 무선 기술 및 테스트베드 개발 동향에 대해서 알아본다.

• Journal of Soil and Groundwater Environment
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• v.13 no.4
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• pp.54-61
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• 2008

Permeable reactive barriers (PRBs) technology has been focused in contaminated groundwater remediation. It is necessary to select adequate reactive material according to characteristics of contaminant in groundwater. In this research, the reaction between reactive material and heavy metal contaminants was estimated through column test. Reactive material was slag, which has been produced in Gwangyang power plant, and heavy metal contaminants were cadmium, lead and copper. Column test was performed in the condition of 1) single and multi contaminated solution and 2) different initial concentration of cadmium. Retardation factor of cadmium is 3.94 in multi contamination. But that of copper is 40.3 in single and 25 in multi. The difference of retardation between cadmium and copper is due to affinity, resulted from the difference of electronegativity. In multi-contamination, copper effluent concentration was above initial copper concentration and at the same time lead effluent concentration was decreased. This phenomenon was considered that lead extract copper sorbed in slag and then lead was sorbed to the vacant sorption site instead. And as the initial concentration was increased, the retardation factor of cadmium became decreased.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2010.11a
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• pp.125-126
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• 2010

채널의 다중경로를 통과한 신호들은 지연확산 영향으로 심하게 왜곡이 되거나 Inter-Symbol Interference(ISI)가 발생하므로 왜곡된 채널을 추정하여 보상해야 한다. 기존 iterative 채널 추정 방식에서는 채널 시간 지연 길이 밖으로 zero padding함으로 노이즈 성분을 제거하는 알고리즘이다. 반면에 본 논문은 채널 시간 지연 길이 안으로 있는 노이즈 성분까지 노이즈 제거 문턱 값 추정(noise elimination threshold estimation: NETE) 알고리즘을 사용하여 노이즈를 효과적으로 제거한다. 시뮬레이션 결과는 채널의 mean square error(MSE)를 통하여 제안된 기법을 적용할 경우 채널 추정 성능 개선이 나타남을 확인할 수 있었다.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.221-222
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• 2009

The results showed that the addition of VAE polymer strongly reduces the $Ca(OH)_2$ formation, being this result attributed to reduce degree of cement hydration caused by different ion elution amount of polymer modified cement pastes and interaction between acetate anion from the partial hydrolysis of co-polymer and Ca$^{2+}$ion from OPC hydration.

• Journal of the Korean GEO-environmental Society
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• v.7 no.1
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• pp.41-53
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• 2006

In this study, estimation of nonlinear adsorption isotherms(Langmuir & Freundlich adsorption isotherm) and advection-dispersion model parameters was conducted using genetic algorithm(GA) for Zn and Cd adsorption. Estimated parameters of nonlinear adsorption isotherms, which were obtained from the optimization process using genetic algorithm(GA), are nearly same with the parameters obtained from a linearization process of the nonlinear isotherms. Estimated effective diffusion coefficients, which were obtained from a finite element analysis of the advection-dispersion model and an optimization procedure using the genetic algorithm, for the metals were approximately in the order of $10^{-7}cm^2/s$ which could be obtained based on the linear distribution coefficient. The effective diffusion coefficients based on the nonlinear retardation factors were in the range of $10^{-6}{\sim}10^{-5}cm^2/s$. As a result, the correlation coefficient obtained between the measured and calculated concentration was over 0.9 which means that the genetic algorithm should be successfully applied to estimate the unknown parameters of the nonlinear adsorption isotherms and advection-dispersion model.

• Fire Science and Engineering
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• v.19 no.2 s.58
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• pp.8-12
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• 2005

A fire in a clean room may cause a serious loss by spreading smoke particles. The effects of the width of smoke curtains on delay in smoke spread, which is located the work area boundaries, were investigated by using a computational fluid dynamics, for loss prevention by smoke spreading from one fire area to another. The fire scenario was set to a 1 MW methanol fire in a space of $30m\times10m$ floor and 4 m high. Distributions of temperature and smoke particles were compared for the width of the smoke curtains 0 (without smoke curtains), 1, 2, 3m. It was confirmed that a larger width of the smoke curtain delays spread of smoke more, and that making the work areas compartments is necessary to confine the smoke in the fire area.

• Fire Science and Engineering
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• v.30 no.5
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• pp.9-17
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• 2016

In the case of a medium length road tunnel, the installation of a smoke control facility is not mandatory so users can suffer considerable injuries if a fire breaks out. Therefore, this study analyzed the high-temperature air and toxic gas generated by fire proliferating with time when a smoke barrier is not installed and when the installation interval is 100, 150, 200, and 250 m through 3-dimensional numerical analysis, evacuation simulation, and Quantitative Risk Assessment Methodology targeting the medium length road tunnel. As a result, the diffusion of the high-temperature air and toxic gas occurring from the a fire was delayed when the smoke barrier was installed in a medium length road tunnel compared to that when it was not installed. In addition, when the installation interval of a smoke barrier was 100m and the numerical analysis target was 100m, the diffusion of high-temperature air and toxic gas generated by the fire was delayed more than in the other cases, which was most suitable for tunnel users to evacuate.