• Proceedings of the Korean Vacuum Society Conference
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• 2005.08a
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• pp.78-78
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• 2005

• Journal of The Korean Society of Grassland and Forage Science
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• v.22 no.1
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• pp.23-30
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• 2002

Eveuadies 71' kenaf (Hibiscus cannabinus L.) was grown at five plant densities (1, 2, 3, 4, and 5 plants per hill; 16,000, 32,000, 48,000, 64,000 and 80,000 plants/10a) from April 13 to October 8, 2001 in Jeju island to determine influence of plant number per hill on agronomic characteristics, forage yield and quality. As plant density increased from 1 to 5 plants per hill, the plant height averaged across two harvests increased 176 to 185 cm. Compared with the plant density of two plants per hill, the plant height decreased at higher plant densities (183, 180, and 166 cm for 3, 4 and 5 plants per hill). The highest yield of fresh forage (114.6 MT/ha), dry matter (17.3 MT/ha), crude protein (2.33 MT/ha), and total digestible nutrients (TDN) (9.21 MT/ha) was obtained at 2 plants per hill. As plant density increased from 1 to 5 plants per hill, crude protein, ether extract, nitrogen free extract, and TDN contents increased from 13.1 to 15.4%, 3.0 to 3.7%, 20.1 to 23.2% and 41.1 to 45.4%, respectively, while crude fiber and crude ash contents decreased from 41.2 to 34.9% and 9.4 to 8.2%, respectively.

• International Journal of Fluid Machinery and Systems
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• v.8 no.3
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• pp.169-182
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• 2015

When simulating the dynamic behaviour of a hydro power plant, it is essential to have a good representation of the turbine behaviour. The pressure transients in the system occurs because the flow changes, which the turbine defines. The flow through the turbine is a function of the pressure, the speed of rotation and the wicket gate opening and is, most often described in a performance diagram or Hill diagram. In the Hill diagram, the efficiency is drawn like contour lines, hence the name. A turbines Hill diagram is obtained by performance tests on scaled model in a laboratory. However, system dynamic simulations have to be performed in the early stage of a project, before the turbine manufacturer has been chosen and the Hill diagram is known. Therefore one have to rely on diagrams for a turbine with similar speed number. The Hill diagram is drawn through measured points, so for using the diagram in a simulation program, one have to iterate in the diagram based on curve fitting of the measured points. This paper describes an alternative method. By means of the Euler turbine equation, it is possible to set up two differential equations which represents the turbine performance with good enough accuracy for the dynamic simulations. The only input is the turbine's main geometry, the runner blade in- and outlet angle and the guide vane angle at best efficiency point of operation (BEP). In the paper, simulated turbine characteristics for a high head Francis turbine, and for a reversible pump turbine are compared with laboratory measured characteristics.

• Journal of Korean Society for Atmospheric Environment
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• v.14 no.3
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• pp.219-228
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• 1998

In the present investigation, a numerical model developed for the prediction of the wind flow over complex terrain is validated by comparing with the field experiments. For the solution of the Reynolds - Averaged Clavier- stokes equations which are the governing equations of the microscale atmospheric flow, the model is constructed based on the finite-volume formulation and the SIMPLEC pressure-correction algorithm for the hydrodynamic computation. The boundary- fitted coordinate system is employed for the detailed depiction of topography. The boundary conditions and the modified turbulence constants suitable for an atmospheric boundary- layer are applied together with the k- s turbulence model. The full- scale experiments of Cooper's Ridge, Kettles Hill and Askervein Hill are chosen as the validation cases . Comparisons of the mean flow field between the field measurements and the predicted results show good agreement. In the simulation of the wind flow over Askervein Hill , the numerical model predicts the three dimensional flow separation in the downslope of the hill including the blockage effect due to neighboring hills . Such a flow behavior has not been simulated by the theoretical predictions. Therefore, the present model may offer the most accurate prediction of flow behavior in the leeside of the hill among the existing theoretical and numerical predictions.

• Journal of Korean Society of Rural Planning
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• v.17 no.3
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• pp.15-25
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• 2011

This paper is to contribute for management and restoration as a basic study of vegetation structure in Aemirang Hill, Nakdongjeongmaek. To verify the characteristics of vegetation structure, we set up 25 plots($100m^2$). The result of community analysis was used by TWINSPAN classification. The communities were classified 7 types i.e. Quercus variabilis community, Quercus mongolica community, Pinus densiflora community, Pinus densiflora-Quercus mongolica community, Q. mongolica-Quercus variabilis community, Quercus mongolica-Betula davurica community, Larix leptolepis community. Pinus densiflora community and Pinus densiflora-Quercus mongolica community are progressively transforming a Quercus mongolica community that is called Pinus densiflora next succession stage. Whereas the communities that has dominant Quercus variabilis and Quercus mongolica did not appear a next generation succession tree such as Carpinus laxiflora, Carpinus cordata in the under story and shrub layer. Therefore, Aemirang Hill's ecological succession was to maintain the status condition. Aemirang Hill's diversity index is 0.5738 to 0.8906. It were analyzed that diversity index was lower than other places.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.3B
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• pp.233-242
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• 2011

This study quantified directional properties of channel network and hill slope for a river basin by applying the von Mises distribution, also examined the relation between them. Ultimately, it was examined that whether the directional properties of channel network and hill slope have a certain relation, which might be considered to the rainfall-runoff modeling. From the results derived by analyzing the Naesung stream basin, the von Mises distribution was found well to explain the directional characteristics of directional properties of channel network. There was a clear relation between directional properties of channel network and hill slope. The higher-order streams also showed very obvious modal characteristics. The results derived in this study could be helpful to estimate more quantitatively the difference in the runoff response with respect to the directional properties of channel network and hill slope.

• Wind and Structures
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• v.19 no.2
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• pp.219-232
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• 2014

The characteristics of turbulent boundary layers over hilly terrain depend strongly on the hill slope and upstream condition, especially inflow turbulence. Numerical simulations are carried out to investigate the neutrally stratified turbulent boundary layer over two-dimensional hills. Two kinds of hill shape, a steep one with stable separation and a low one without stable separation, two kinds of inflow condition, laminar turbulent, are considered. An auxiliary simulation, based on the local differential quadrature method and recycling technique, is performed to simulate the inflow turbulence be imposed at inlet boundary of the turbulent inflow, which preserves very well in the computational domain. A large separation bubble is established on the leeside of the steep hill with laminar inflow, while reattachment point moves upstream under turbulent inflow condition. There is stable separation on the side of low hill with laminar inflow, whilw not turbulent inflow. Besides increase of turbulence intensity, inflow can efficiently enhance the speedup around hills. So in practice, it is unreasonable to study wind flow over hilly terrain without considering inflow turbulence.

• Tunnel and Underground Space
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• v.23 no.6
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• pp.547-560
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• 2013

The importance of renewable energy has increased continuously due to the energy insecurity and the necessity of reducing carbon dioxide which is causing global climate change. In such a situation, the Pohang Enhanced Geothermal System (EGS) power plant project which is launched in December 2010 shall be a new opportunity for the development of EGS related technologies in Korea. In this paper, the case studies of Fenton Hill project in the USA and Hijiori project in Japan are introduced in order to help a part of the domestic EGS demonstration project. As a result, it could be helpful to minimize the trial and error of the domestic EGS project by acquiring the achievements and limitations of existing EGS projects.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.24 no.2
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• pp.57-63
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• 1979

This study has been carried out to find out the optimum plant density and number of seedling per hill in the late season culture of rice at Chung Buk. P.O.R.D. Up to the level of 33 hills per m2 and 6 number of seedling per hill, rice yield was increased as the number of seedling per hill and plant density per unit areas increased. However it is recommendable to have a plant density of 28~33 hills per m$^2$ with 4~6 number of seedling per hill for the late season culture.

• Journal of Korean Society for Atmospheric Environment
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• v.12 no.4
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• pp.459-472
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• 1996

An experimental investigation on the wind flow over smooth bell-shaped two-dimensional hills with hill slopes (the ratio of height to half width) of 0.3 and 0.5 is performed in an atmospheric boundary-layer wind tunnel. Two categories of the models are used in the present investigation; six two-dimensional single-hills, and four continuous double-hills. The measurements of the flow field and surface static-pressure distribution are carried out over the Reynolds number (based on the hill height) of 1.9 $\times 10^4, 3.3 \times 10^4, and 5.6 \times 10^4$. The velocity profiles and turbulence characteristics are measured by the pitot-tube and X-type hot-wire anemometer, respectively. The undisturbed boundary-layer profile on the bottom surface of the wind tunnel is reasonably consistent with the power-law profile with $\alpha = 7.0 (1/\alpha$ is the power-law exponent) and shows good spanwise uniformities. The profiles of turbulent intensity are found to be consistent along the centerline of the wind tunnel. The measured non-dimensional speed-up profiles at the hill crest show good agreements with the predictions of Jackson and Hunt's linear theory. The flow separation occurs in the hill slope of 0.5, and the oil-ink dot method is used to find the reattachment points in the leeside of the hill. The measured reattachment points are compared with the numerical predictions. Comparisons of the mean velocity profiles and surface pressure distributions between the numerical predictions and the experimental results show good agreements.