• Bulletin of the Korean Chemical Society
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• 제35권9호
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• pp.2679-2683
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• 2014

Mechanisms underlying the impacts of interactions between carbon nanoparticles (CNPs) and ionic liquids (ILs) on the physicochemical behavior of CNPs need to be more full worked out. This manuscript describes a theoretical investigation at multiple levels on the interactions of fullerene $C_{60}$ with 21 imidazolium-based ILs of varying alkyl side chain lengths and anionic types and their impacts on $C_{60}$ dispersion behavior. Results show that ${\pi}$-cation interaction contributed to mechanism of the $C_{60}$-IL interaction more than ${\pi}$-anion interaction. The calculated interaction energy ($E_{INT}$) indicates that $C_{60}$ can form stable complex with each IL molecule. Moreover, the direction of charge transfer occurred from IL to $C_{60}$ during the $C_{60}$-IL interaction. Quantitative models were developed to evaluate the self-diffusion coefficient of $C_{60}$ ($D_{fullerene}$) in bulk ILs. Three interpretative molecular descriptors (heat of formation, $E_{INT}$, and charge) that describe the $C_{60}$-IL interactions and the alkyl side chain length were found to be determinants affecting $D_{fullerene}$.

• 한국환경과학회지
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• 제14권9호
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• pp.851-860
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• 2005

In order to how well predict ISCST3(lndustrial Source Complex Short Term version 3) model dispersion of air pollutant at point source, sensitivity was analysed necessary parameters change. ISCST3 model is Gaussian plume model. Model calculation was performed with change of the wind speed, atmospheric stability and mixing height while the wind direction and ambient temperature are fixed. Fixed factors are wind direction as the south wind(l80") and temperature as 298 K(25 "C). Model's sensitivity is analyzed as wind speed, atmospheric stability and mixing height change. Data of stack are input by inner diameter of 2m, stack height of 30m, emission temperature of 40 "C, outlet velocity of 10m/s. On the whole, main factor which affects in atmospheric dispersion is wind speed and atmospheric stability at ISCST3 model. However it is effect of atmospheric stability rather than effect of distance downwind. Factor that exert big influence in determining point of maximum concentration is wind speed. Meanwhile, influence of mixing height is a little or almost not.

• 한국지반공학회지:지반
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• 제13권3호
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• pp.53-62
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• 1997

주파수영역 표면파기법 (SASW)을 수중지반탐사에 적용하기 위한 일련의 해석적 연구가 실시되었다. SASW실험으로 지반강도분포를 정밀히 예측하기 위해서는 실험조건, 고차모드의 영향, 응답파의 정리 기법 등, 실험결과에 영향을 미치는 모든 제반 요소들을 고려한 정확하고도 경제적인 이론분산곡선을 결정해야만 한다. 따라서, 본 논문에서는 수중 표면파의 이론분산곡선을 구하기 위한 해석기법들을 개발하고 그 이론적 배경을 설명하였다. 또한, 개발된 해석기법들을 수중지반에서 실제로 실시된 SASW실험결과의 분석에 적용하여 수중지반의 강도특성을 예측하는 예를 보였다. 이 결과로부터 개발된 해석기법들과 더불어서 수중지반탐사를 위한 SASW 실험방법의 적용성이 검토되었다.

• 국제초고층학회논문집
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• 제1권2호
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• pp.87-97
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• 2012

The indoor environments in high-rise buildings are generally well enclosed by defined boundary conditions. Here, a numerical simulation method based on the Lattice Boltzmann method (LBM), which aims to model and simulate the turbulent flow accurately in an enclosed environment, and its comparison with traditional computational fluid dynamics (CFD) results, are presented in this paper. CFD has become a powerful tool for predicting and evaluating enclosed airflows with the rapid advance in computer capacity and speed, and various types of CFD turbulence modeling and its application and validation have been reported. The LBM is a relatively new method; it involves solving of the discrete Boltzmann equation to simulate the fluid flow with a collision model instead of solving Navier-Stokes equations. In this study, the LBM-based scheme of flow pattern and particle dispersion analyses are validated using the benchmark test case of two- and three-dimensional and isothermal conditions (IEA/Annex 20 case); the prediction accuracy and advantages are also discussed by comparison with the results of CFD.

• Wind and Structures
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• 제27권6호
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• pp.417-430
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• 2018

The concentration fields in the proximities of a local gas emission source are experimentally analyzed in several combinations of wind incidences and source emissions. These conditions are determined by the plume buoyancy, emission velocity and incident flow wind speed. Concentration measurements are performed by an aspirating probe in a boundary layer wind tunnel. The analysis included the mean concentration values and the intensity of concentration fluctuations in a neutral atmospheric boundary layer flow. Different configurations are tested: an isolated stack in a homogeneous terrain and a stack with a bluff body in close proximity, located windward and leeward from the emission source. The experimental mean concentration values are contrasted with Gaussian profiles and the dilution factor is analyzed with respect to the empirical curves of the minimum dilution. Finally, a study on the plume intermittency is performed in a cross-sectional plane near the emission source. It is possible to highlight the following observations: a) plume vertical asymmetry in the case of an isolated emission source, b) significant differences in the dispersion process related to the relative location of the emission source and bluff body effects, and c) different probabilistic behavior of the concentration fluctuation data in a cross-sectional measurement plane inside the plume.

• 한국응용과학기술학회지
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• 제33권3호
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• pp.529-539
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• 2016

Modeling은 기상의 흐름, 화학반응 및 대기오염물질의 형성과정 등 대기현상을 과학적으로 이해하고 개발계획 및 대기 개선에 따른 정책수립의 기초자료로 활용된다. 최근 컴퓨팅 계산능력이 발전하면서 수치모델의 모델링 영역과 모델결과의 이용분야가 점차 다양해지고 있으며, 오염물질 발생원으로부터 시간의 흐름에 따라 오염물질농도를 예측이 가능해졌다. 본 연구는 일산열병합발전소 및 고양시 소각장 주변지역을 대상으로 CALPUFF 확산모델을 적용하여 대기 중 배출 된 NO와 TSP의 확산을 모사하고, 실제 측정결과와 비교함으로써 배출원에 의한 주변지역의 기여농도를 검토하였다. 1, 2차 $NO_2$ 기여율 비교 결과 A-3 지점이 타 지점에 비해 비교적 높게 나타났으며, 이는 열병합발전소 및 소각시설에서 배출되는 질소산화물의 영향이 타 지역에 비해 비교적 높다는 것을 알 수 있다. 1, 2차 TSP 기여율 비교 결과 A-5 지점이 비교적 타 지점에 비해 다소 높게 나타났으나, 기여율 값이 매우 낮음에 따라 열병합발전소 및 소각시설에서 배출되는 먼지에 의한 영향은 비교적 낮다고 판단된다.

• 한국전자통신학회논문지
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• 제10권1호
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• pp.47-54
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• 2015

최근, 산업화와 도시화로 연료소비가 급격하게 증가하고, 주요 도시들의 대기오염이 심화됨에 따라 대기질 관리를 위해 대기확산모델의 이용 및 개발과 관련된 연구들이 다양하게 진행되고 있다. 본 연구에서는 국내에서 U.S. EPA가 제공하는 대기확산모델의 활용범위 확장을 목적으로 국내 기상자료를 미국 자료체계로의 변환기능과 모델입력용 기상자료의 생성이 가능한 "국내 기상자료 전처리 프로그램"을 개발하고, 사례연구에 적용을 통해서 프로그램의 활용성을 평가하였다. 평가 결과, 국내 기상자료를 미국 자료체계로 정확하게 변환처리하고, 대기질 모델링 과정에서 오류의 발생 없이 예측이 가능하여 향후 국내 기상자료 전처리 도구로 높은 활용성을 나타내었다.

• 환경영향평가
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• 제16권6호
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• pp.381-391
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• 2007

The air quality modeling was carried out to assess the impact of air quality for large scale urban development. The site for the assessment is Multi-fuctional Administrative City which locates in Yeongi-gun, Chungcheongnam-do and estimated population in 2030 is 500,000. Two automatic weather monitoring stations were installed to monitor the meteorological variables for a year and upper air meteorological parameters were measured using radiosonde for 5 days with 4 hours interval in every season. The air quality of standard air pollutants were also measured for 5 days continuously in every season. The results of wind field analysis based on the site measurements and CALMET modeling showed that the valley and mountain winds were prevailed when the sypnotic wind was weak. It also showed that wind speed and directions were highly space-variable within the site basin. The variable wind characteristics implies that the Gaussian dispersion model such ISC3 and AERMOD are not appropriate and the unsteady-sate Lagrangian model such as CALPUFF is preferable. CALPUFF model was applied to assess air quality impact of new sources. The new sources were those for individual and group heating facilities as well as the traffic increases. The results showed that the estimated concentrations of CO and $SO_2$ pollutants by summing the impact concentration of new sources by the dispersion model and the ambient air concentrations by the site measurements were acceptable but those of PM-10 and $NO_2$ would violate ambient air quality standards at several locations due to high ambient air concentrations. It is recommended that the emission reductions near the site should be enforced to improve the ambient air quality.

• Nuclear Engineering and Technology
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• 제45권7호
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• pp.827-838
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• 2013

Interaction layer growth between U-Mo alloy fuel particles and Al in a dispersion fuel is a concern due to the volume expansion and other unfavorable irradiation behavior of the interaction product. To reduce interaction layer (IL) growth, a small amount of Si is added to the Al. As a result, IL growth is affected by the Si content in the Al matrix. In order to predict IL growth during fabrication and irradiation, empirical models were developed. For IL growth prediction during fabrication and any follow-on heating process before irradiation, out-of-pile heating test data were used to develop kinetic correlations. Two out-of-pile correlations, one for the pure Al matrix and the other for the Al matrix with Si addition, respectively, were developed, which are Arrhenius equations that include temperature and time. For IL growth predictions during irradiation, the out-of-pile correlations were modified to include a fission-rate term to consider fission enhanced diffusion, and multiplication factors to incorporate the Si addition effect and the effect of the Mo content. The in-pile correlation is applicable for a pure Al matrix and an Al matrix with the Si content up to 8 wt%, for fuel temperatures up to $200^{\circ}C$, and for Mo content in the range of 6 - 10wt%. In order to cover these ranges, in-pile data were included in modeling from various tests, such as the US RERTR-4, -5, -6, -7 and -9 tests and Korea's KOMO-4 test, that were designed to systematically examine the effects of the fission rate, temperature, Si content in Al matrix, and Mo content in U-Mo particles. A model converting the IL thickness to the IL volume fraction in the meat was also developed.

• 한국해안·해양공학회논문집
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• 제27권2호
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• pp.79-93
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• 2015

Gulf Stream 인근해역에서 해양 중규모 와동의 삼차원 구조분석을 HYCOM 수치모델을 사용하여 수행하였다. 시계방향 및 반시계 방향으로 회전하는 와동들의 구조를$1/12^{\circ}$와 $1/48^{\circ}$ 두개의 모델 해상도를 사용하여 비교하였다. 라그랑지안 모수인 Finite Size Lyapunov Exponent (FSLE) 와 Okubo-Weiss parameter(OW) 분포를 분석한 결과 표층의 와동구조가 수심 깊은 곳까지 영향을 미치는 것으로 나타났는데, 이는 와동에 의한 수평방향 해수운동이 수직방향 해수운동보다 크기 때문인 것으로 해석되었다. 고해상도 모델의 경우 와동근처에서 10 km 미만의 미세난류구조 들이 많이 발견되었으며, 이러한 미세난류구조들은 고해상도 모델의 와동근처에서 해수의 움직임을 저해상도 모델보다 불규칙하게 만드는 것으로 나타났다. 이러한 미세난류구조에 의한 해수의 불규칙한 움직임은 분산계수 (dispersion coefficient)에도 영향을 미치는데, 수평 분산계수의 경우 해수운동이 자유로운 고해상도 모델이 저해상도 모델보다 그 값이 더 크게 나타났다. 수직 분산계수의 값은 저해상도 모델에서 더 크게 나왔는데, 이는 와동의 경사진 궤도를 따라 움직이는 저해상도 모델의 해수운동이 수직 분산계수값을 증가시키기 때문인 것으로 들어났다. 상대 수직 분산계수의 경우 이러한 궤도의 영향이 줄어들기 때문에 해수의 수직운동을 측정하는데 있어 절대 수직 분산계수 보다 더 적합한 것으로 판명되었다.