• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권3호
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• pp.990-1013
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• 2015

Deploying sensors into a target region is a key issue to be solved in building a wireless sensor network. Various deployment algorithms have been proposed by the researchers, and most of them are evaluated under the ideal conditions. Therefore, they cannot reflect the real environment encountered during the deployment. Moreover, it is almost impossible to evaluate an algorithm through practical deployment. Because the deployment of sensor networks require a lot of nodes, and some deployment areas are dangerous for human. This paper proposes a deployment approach to solve the problems mentioned above. Our approach relies on the satellite images and the Virtual Force Algorithm (VFA). It first extracts the topography and elevation information of the deployment area from the high resolution satellite images, and then deploys nodes on them with an improved VFA. The simulation results show that the coverage rate of our method is approximately 15% higher than that of the classical VFA in complex environment.

• Animal cells and systems
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• 제6권1호
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• pp.59-64
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• 2002

To restore the forest ecosystem severely damaged by air pollution around industrial complexes, plants tolerant to the polluted environment were selected by transplant and pot culture experiments. A restoration plan by arranging those tolerant species was prepared based on the ecological diagnostic results on an area that requires restoration. Transplant experiment in Ulsan and Yeocheon areas, the representative industrial complexes in Korea, selected eight tolerant species of Quercus aliena, Q. acutissima, Q. dentata, Q. mongolica, Q. serrata, Ligustrum japonicum, Styrax japonica, and Poncirus trifoliata. Cultivation in the polluted soil transported from the Ulsan and Yeocheon industrial complexes chose five tolerant plants of Q. aliena, Q. acutissima, Q. serrata, Styrax japonica, and Alnus firma. A plan to restore the forest ecosystem of Mt. Dotjil, which experienced the severest ecosystem degradation in the Ulsan industrial complex, was prepared by applying those tolerant species along with treatment for soil amelioration. Arrangement of the tolerant species was designed by considering their ecological characteristics including distribution range on topography and shade tolerance. Soil amelioration was focused on the improvement of fertility and moisture conditions.

• Wind and Structures
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• 제10권6호
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• pp.543-554
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• 2007

The suspension bridge is situated in an area of complex topography with both open sea and overland turbulence characteristics, and it is subject to frequent typhoon occurrences. This paper investigates experimentally the possible vortex shedding events of the structure under high wind and typhoon conditions. A single-degree-of-freedom model for the vibration of a unit bridge deck section is adopted to determine the amplitude of vibration and to estimate the parameters related to the lifting force in a vortex shedding event. The results of the studies are presented in a companion paper (Law, et al. 2007). In this paper, statistical analysis on the measured responses of the bridge deck shows that the vibration response at the first torsional mode of the structure has a significant increase at and beyond the critical wind speed for vortex shedding as noted in the wind tunnel tests on a section model of the structure.

• 한국해안해양공학회지
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• 제7권4호
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• pp.321-328
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• 1995

PCGS(preconditioned conjugate squared) 방법을 사용한 음해법적 조석모형인 FIT(fully implicit tidal)모형을 개발하여 목포항 인근해역에 적용하였다. M$_2$분조에 따른 유속과 조위에 대한 검증결과 만족할 만한 결과를 얻었으며, 빠른 유속을 갖는 협수부와 수심과 지형이 복잡한 곳에서도 모형의 타당성이 입증되었다. 개발된 모형을 통해 목포구의 완충효과를 규명하여 하구언 및 방조제 건설에 따른 목포항 부근의 조석 확폭현상을 파악할 수 있었다.

• 한국농공학회지
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• 제43권2호
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• pp.69-77
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• 2001

An artificial neural network model was developed to analyze and forecast daily steamflow flow a small watershed. Error Back propagation neural networks (EBPN) of daily rainfall and runoff data were found to have a high performance in simulating stremflow. The model adopts a gradient descent method where the momentum and adaptive learning rate concepts were employed to minimize local minima value problems and speed up the convergence of EBP method. The number of hidden nodes was optimized using Bayesian information criterion. The resulting optimal EBPN model for forecasting daily streamflow consists of three rainfall and four runoff data (Model34), and the best number of the hidden nodes were found to be 13. The proposed model simulates the daily streamflow satisfactorily by comparison compared to the observed data at the HS#3 watershed of the Baran watershed project, which is 391.8 ha and has relatively steep topography and complex land use.

• 농촌계획
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• 제7권1호
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• pp.15-25
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• 2001

This paper described the overall operations and applications of the water environment management and evaluation systems (WEMES) for environmental management, conservation, and evaluation for a small watershed. WEMES was to be applied with field data from small watersheds ranging from 0.4 to 29.79km2 in size which have steep topography and complex landuses. WEMES was a computer aided decision support system, that was comprised of the database subsystem, the simulation model subsystem, the environmental evaluation model subsystem, and the graphic user interface subsystem that visualizes the simulated results. The water environment management and evaluation with WEMES was successfully performed.

• 산업기술연구
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• 제3권
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• pp.9-15
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• 1983

To detect faulted coal seam, two and three dimensional model experiments were conducted. The size of three dimensional water tank is $170cm{\times}80cm{\times}95cm$ and the size of model coal seam is $20cm{\times}50cm{\times}1cm$ carbon plate. In this paper, various potential curves were made changing distance and model size from surface. Using these curves, interpretation of faulting coal explotation in complex topography can be done by comparing field data each other.

• 한국대기환경학회지
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• 제11권2호
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• pp.145-152
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• 1995

Predictability of a Gaussian model, ISCST2 was assessed by scaling up wind tunnel experiments with a 1/3,000 terrain model to the real scale. Concentration profiles obtained from the flat-terrain experiment in the neutral condition were estimated to be in agreement with the calculated ones from ISCST2 in the stability class A, but the difference between the two was still large. Concentration profiles from the mountainous-terrain experiments were better fitted to the calculated ones primarily because in the experiment, concentration behind the source was raised due to the effect of a hill in the upstream side. Model prediction was improved with including the downwash effect of buildings and the hill, but overall concentration profiles were not much different from a typical Gaussian profile. While concentration profiles in the experiments were changed with local flows by varying the wind direction and the topography, those from the Gaussian modeling were mot freely changed together with these variations.

• 한국가시화정보학회지
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• 제8권1호
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• pp.13-18
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• 2010

An experimental investigation of the flow around a vertical fence was carried out using a PIV velocity field measurement technique. The vertical fence was embedded in a turbulent boundary layer. The instantaneous velocity fields measured at cross-sectional planes reveal complex longitudinal vortices that vary in size and strength, developing from the upstream location. In the instantaneous vorticity and velocity field data, the shear flow separated from the fence top is highly turbulent and shows unsteady flow characteristics. The topography of the ensemble averaged velocity fields, especially the separation bubble formed behind the fence, shows that the spatial distributions of streamwise velocity (U) and vertical (V) are symmetric, the spanwise velocity (W) is skew-symmetric with respect to the central xy-plane(z=0).

• Wind and Structures
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• 제29권1호
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• pp.55-64
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• 2019

The effect of vortex impingement on the fluid dynamics around a cylinder submerged in the wake of another of different diameters is numerically investigated at a Reynolds number Re = 200. While the diameter (D) of the downstream cylinder is fixed, impinging vortices are produced from the upstream cylinder diameter (d) varied as d/D = 0.24, 0.4, 0.6, 0.8 and 1.0, with a spacing ratio L=5.5d, where L is the distance between the center of the upstream cylinder to the front stagnation point of the downstream cylinder. Two-dimensional simulations are carried out using the finite volume method. Fluid forces acting on the two cylinders are correlated with impinging vortices, vortex shedding, and wake structure. Different facets of wake formation, wake structure, and flow separation and their connections to fluid forces are discussed.