• International Journal of Highway Engineering
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• v.10 no.4
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• pp.79-89
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• 2008

The pavement performance model is the most important factor to determine the pavement life in the mechanistic-empirical pavement design guide (MEPDG). As part of Korean Pavement Research Program (KPRP), the Korean Pavement Design Guide (KPDG) is currently being developed based on mechanistic-empirical principle. In this paper, the rutting prediction model of asphalt mixtures, one of the pavement performance model, has been developed using triaxial repeated loading testing data. This test was conducted on various types of asphalt mixtures for investigating the rutting characteristics by varying with the temperature and air void. The calibration process was made for the coefficients of rutting prediction model using the accelerated pavement testing data. The accuracy of prediction model can be increased when by considering the effect of individual rutting properties of materials rather than shear stresses with depths.

• Journal of Radiation Protection and Research
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• v.27 no.3
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• pp.171-179
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• 2002

The three-dimensional long-range dispersion model has been developed to understand the characteristics of the transport and diffusion of radioactive materials released into atmosphere. The model is designed to compute air concentration and ground deposition at distances up to some thousands of kilometers from the source point in horizontal direction. The vertical turbulent motion is considered separately within the mixing layer and above the mixing layer. The test simulation was performed In the area of Northeast Asia. The release point was assumed in the east part of China. The calculated concentration distributions art mainly advected toward the southeast part of release point by the wind fields. The developed model will be used to estimate the radiological consequences against a nuclear accident. The model will be supplemented by the comparative study using the data of the long-range field experiments.

• Journal of the Korean Institute of Intelligent Systems
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• v.17 no.4
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• pp.435-442
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• 2007

To reduce damage from high concentration ozone in the air, we have researched how to predict high concentration ozone before it occurs. High concentration ozone is a rare event and its reaction mechanism has nonlinearities and complexities. In this paper, we have tried to apply and consider as many methods as we could. We clustered the data using the fuzzy c-mean method and took a rejection sampling to fill in the missing and abnormal data. Next, correlations of the input component and output ozone concentration were calculated to transform more correlated components by modified log transformation. Then, we made the prediction models using Dynamic Polynomial Neural Networks. To select the optimal model, we adopted a minimum bias criterion. Finally, to evaluate suggested models, we compared the two models. One model was trained and tested by the transformed data and the other was not. We concluded that the modified transformation effected good to ideal performance In some evaluations. In particular, the data were related to seasonal characteristics or its variation trends.

• Composites Research
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• v.22 no.3
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• pp.44-54
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• 2009

In this paper, we proposed a numerical model the complex permittivity for the E-glass fabric/epoxy composite laminate containing electrical conductive carbon black. The model is based on the percolation theory and for the composites over than the percolation threshold and in higher frequency band in that the AC conductivity is fully proportional to the frequency. The measurement for the complex permittivity wasperformed at the frequency band of 0.5 GHz $\sim$ 18.0 GHz using a vector network analyzer with a 7 mm coaxial air line. The proposed model is composed of the numerical equations of the scaling law used in percolation theory and constants obtained from experiments to quantify the model itself. The model describes the complex permittivity as the function of frequency and filler concentration. The model was verified by being compared with the measurements.

• Journal of Bio-Environment Control
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• v.15 no.4
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• pp.296-305
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• 2006

The heterogeneity of crop transpiration is important to clearly understand the microclimate mechanisms and to efficiently handle the water resource in greenhouses. A computational fluid dynamic program (Fluent CFD version 6.2) was developed to study the internal climate and crop transpiration distributions of greenhouses. Additionally, the global solar radiation model and a crop heat exchange model were programmed together. Those models programmed using $C^{++}$ software were connected to the CFD main module using the user define function (UDF) technology. For the developed CFD validity, a field experiment was conducted at a $17{\times}6 m^2$ plastic-covered mechanically ventilated single-span greenhouse located at Pusan in Korea. The CFD internal distributions of air temperature, relative humidity, and air velocity at 1m height were validated against the experimental results. The CFD computed results were in close agreement with the measured distributions of the air temperature, relative humidity, and air velocity along the greenhouse. The averaged errors of their CFD computed results were 2.2%,2.1%, and 7.7%, respectively.

• Journal of Korean Society for Atmospheric Environment
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• v.7 no.3
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• pp.189-196
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• 1991

In recent years spectral methods have been found to be a powerful tool for the numerical solution of hynamic differential equations. The main attraction of spectral method is accuracy even though it is generally difficult to implement and solve the complex problems using spectral method. We introduced diffusion equations describing the state of air pollution and solved by pseutospectral method in dimensionless form. The results were compared with both those of other numerical methods and analytical solutions. Comparing with finite difference method and finite element method, spectral method shows the highest accuracy for one dimension problem in this study. Also, the results of two dimensional diffusion problems show good agreement with analytical solutions.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2003.05b
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• pp.347-348
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• 2003

대기 중의 질산에 의해 생성되는 질산염은 해염성분이나 토양성분과 만나 조대입자 영역에 머물거나 암모늄과 만나 미세입자로 존재할 수 있다. 미세입자로 존재하는 질산염은 여름철과 같은 광화학 반응이 활발할 때 2차적으로 생성되는 물질로, 반휘발성 특성 때문에 측정하는 과정에서 오차가 발생할 가능성도 크다. Seinfeld (1986)에 의하면 미국의 도심 지역에서 미세입자 중 황산염이나 질산염 등 2차 이온 성분의 비율이 전체 입자의 40∼60 %를 차지한다고 보고되고 있으며, 대표적인 도심 지역인 서울에서도 비슷하다 (강충민 등, 1999). (중략)

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2003.05b
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• pp.364-365
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• 2003

모델에 입력되는 지형자료의 형태는 좌표별 고도가 체계적으로 정리된 DEM(Digital Elevation Model)형태를 사용할 수 있으며, 과거에는 이러한 지형자료를 얻기 위해 대상지역의 지형도 중 등고선을 대상으로 좌표별 고도수치를 정리하여 구축하거나, 섬세한 지형자료를 구축하고자 할 경우 각 고도별 등고선자료를 scan한 후에 각 등고선별 고도자료의 위상관계를 설정해 주는 작업을 진행하였으나, 두 방법 모두 상당량의 수정작업과 반복작업이 요구되는 단점을 갖고 있었다. 그러나 국립지리원 주도로 1998년 9월부터 시작된 NGIS(National Geogralhic Information Sydtem)사업에 의해 구축된 수치지도를 이용하여 등고선별 고도자료를 추출하고, 이를 가공하여 모델의 입력자료로 활용하는 방법이 최근에 소개되고 있으며, 지형자료의 구축에 소요되는 시간 및 정확한 자료를 구축할 수 있다. (중략)

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.5
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• pp.30-37
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• 2001

Most gasoline engines employ a port injection system to achieve the better fuel-air mixing. A part of injected fuels adheres to the wall or intake valve and forms a film of liquid fuel. The other is secondarily atomized by the spray-wall interaction. A better understanding of this interaction will help in designing injection systems and controlling the strategies to improve engine performance and exhaust emissions. In the present research, the spray-wall interaction was investigated by a laser sheet visualization method. The shape of sprays was pictured at various impinging velocities and angles. The fuel dispersion was estimated by fluorescence light, and the atomization was evaluated by the enlarged images of droplets. The experimental results were compared with model predictions which are based on OPT method. The model has been modified to have the better agreement with the experimental result, and was implemented in the KIVA-II code.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10c
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• pp.238-240
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• 2003

SDR(Software Defined Radio) 시스템의 발전으로 단말기와 기지국 장비의 교체 없이 서로 다른 표준안을 요구하는 서비스에 대해서 해당 컴포넌트들을 다운로드하고 동적으로 시스템을 재구성하여 해당 서비스에 맞는 시스템을 구성할 수 있다. SDR 시스템의 기본 기능에는 사용하고자 하는 컴포넌트를 여러 가지 방법에 따라 다운로드하는 것이 포함 될 수 있다. 다운로드 할 필요가 있는 컴포넌트는 크게 상용과 공개용으로 나눠 볼 수 있는데 기본적으로 안티­바이러스 패치나 해당 사업자의 중요한 소프트웨어 패치 등의 공개용 컴포넌트를 효율적으로 다운로드 하여 재구성하는 방안이 우선적으로 요구된다. 본 논문에서는 OTA(Over The Air)를 통해 다운로드 하고자 하는 경우를 중심으로. Server/Client 모델의 일 대 일 방식의 다운로드 방식보다 네트워크 자원 및 트래픽의 효율적인 사용을 위해 Ad hoc 모델을 이용하여 다운로드하는 알고리즘을 제안하였다.