• Journal of Korea Water Resources Association
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• v.44 no.6
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• pp.429-438
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• 2011

In order to simulate a free surface flow in a trench channel, a three-dimensional incompressible unsteady Reynolds-averaged Navier-Stokes (RANS) equations are closed with the ${\kappa}-{\epsilon}$ model. The artificial compressibility (AC) method is used. Because the pressure fields can be coupled directly with the velocity fields, the incompressible Navier-Stokes (INS) equations can be solved for the unknown variables such as velocity components and pressure. The governing equations are discretized in a conservation form using a second order accurate finite volume method on non-staggered grids. In order to prevent the oscillatory behavior of computed solutions known as odd-even decoupling, an artificial dissipation using the flux-difference splitting upwind scheme is applied. To enhance the efficiency and robustness of the numerical algorithm, the implicit method of the Beam and Warming method is employed. The treatment of the free surface, so-called interface-tracking method, is proposed using the free surface evolution equation and the kinematic free surface boundary conditions at the free surface instead of the dynamic free surface boundary condition. AC method in this paper can be applied only to the hydrodynamic pressure using the decomposition into hydrostatic pressure and hydrodynamic pressure components. In this study, the boundary-fitted grids are used and advanced each time the free surface moved. The accuracy of our RANS solver is compared with the laboratory experimental and numerical data for a fully turbulent shallow-water trench flow. The algorithm yields practically identical velocity profiles that are in good overall agreement with the laboratory experimental measurement for the turbulent flow.

• Journal of the Korean Institute of Landscape Architecture
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• v.28 no.3
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• pp.105-115
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• 2000

The purpose of paper is to investigate the characteristics of regulations on landscape management of historic city of Kyongju in Korea, compared with those of Nara in japan to answer the research question that what is the regulative characteristics of landscape management of historic city in Korea. We have analyzed the three laws of the two country - Urban Planning Law, Cultural Assets Protection law, and Building Law. This research has been done in terms of regulative systems of the two country and articles, ordinances, and bylaws on landscape managements of historic city Major components of urban historic landscape management are goals and devices of preservation, preserving actor, authorized actor permitting major planning change, regulatory power on landscape development, and backgrounds of enacting regulations. From this research, we have fond the fact that 1) Kyongju City has general and implicit objectives of landscape management based on conservation of natural environment while Nara City has concrete objectives of lansdscape management, 2) Kyongju City has no regulations on landscape planning while Nara City has systematic planning measures such as designation of landscape management district, planning for preservation of historic landscape, and planning for establishing urban landscape, 3) In an application of landscape management district, Kyongju City designate the district based on the general principle of urban planning district while nara City designate it in a more detailed manner such as district of preservation of historic landscape, district of landscape establishment, and district of building agreement. 4) Kyongju has no legal actor in implementation and management of historic landscape plan while Nara City has administrative organization and procedures, including citizen participation, public hearing, and voluntary participation, and 5) Kyongju City does not operate the consultation committee on landscape management just like Nara City operating. This research results will provide us the remedial insights for landscape preservation of such Korean historic city as Kongju, Puyo, and Chunju. Since our research is focused on the limited area of preserving landscape in historic cities in korea and Japan we need to study sociocultural issues on preserving urban historic landscape more in depth in the future.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.11
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• pp.2786-2791
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• 2014

This paper describes the smart illuminating system based on the obstacle environmental presetting to improve the user convenience to easy lighting and energy conservation. Obstacle environment has trouble controlling the illuminating equipment using manual buttons in certain circumstances, which requires a smart remote controller. The smart remote controller is operated by the smart phone, motion sensor and timer to turn on and off the lamps. The event sensor module transmits the signals of the event occurrence to equipment on the remote place when smart phone and motion sensor detect an event, and the illuminator received the event turn on or off the lamp. The system results in energy saving by simple on/off control and manipulating the operating time with controlling the illuminating system preset by user's obstacle or preference circumstances. The proposed system implementation is experimented to figure out the energy saving about13.5w/h and the optimized convenience control.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.1003-1005
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• 2003

In this paper, 3-D nonlinear electromagnetic analysis of a single phase 1MVA 22.9 kV/6.6 kV high temperature superconducting(HTS) transformer with double pancake windings was accomplished. The characteristics of 1MVA HTS transformer such as The efficiency, voltage regulation and % impedance voltage drop were obtained by the 3-D non-linear electromagnetic analysis. And in order to verify the 3-D non-linear electromagnetic analysis of a single phase 1MVA HTS transformer, a 1MVA test transformer with windings made of copper tapes with the same size as BSCCO-2223 HTS tape was manufactured. The energy conservation method to perform the analysis of leakage impedances of both a 1MVA HTS transformer and test transformer was used. The characteristic analysis such as efficiency, voltage regulation and % impedance voltage drop of transformer was performed. And the obtained values of both 1MVA HTS transformer and test transformer were compared.

• Proceedings of the KIEE Conference
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• 2009.04b
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• pp.29-31
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• 2009

Optimal efficiency control of synchronous reluctance motor(SynRM) is very important in the sense of energy saving and conservation of natural environment because the efficiency of the SynRM is generally lower than that of other types of AC motors. This paper is proposed an efficiency optimization control for the SynRM which minimizes the copper and iron losses. The design of the speed controller based on fuzzy-neural networks (FN)-PI controller that is implemented using fuzzy control and neural networks. There exists a variety of combinations of d and q-axis current which provide a specific motor torque. The objective of the efficiency optimization control is to seek a combination of d and q-axis current components, which provides minimum losses at a certain operating point in steady state. It is shown that the current components which directly govern the torque production have been very well regulated by the efficiency optimization control scheme. The proposed algorithm allows the electromagnetic losses In variable speed and torque drives to be reduced while keeping good torque control dynamics. The control performance of the proposed controller is evaluated by analysis for various operating conditions. Analysis results are presented to show the validity of the proposed algorithm.

• Environmental and Resource Economics Review
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• v.20 no.4
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• pp.761-796
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• 2011

The purpose of this paper is to derive fuel mix of electricity generating system with the lowest cost considering energy security and climate change mitigations as the target of energy policy. Energy Security Price Index(ESPI), based on the measure of market concentration in fossil fuel market and political risk of exporting countries, is chosen to assess the level of energy security. The methodology of Energy Conservation Supply Curve(CSC) is applied to fuel mix to meet the carbon emission mitigation through increasing the alternatives participation and introduction of new technologies. These also represent an improvement on the level of energy security, having the complementarity between two objectives. The alternative measure for improving energy security is exploration and production(E&P) of fossil fuel for energy sufficiency. Fuel mix of electricity generating system to achieve certain objectives in 2020 can be derived with the lowest cost considering energy security and carbon emission mitigations.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.12 no.3
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• pp.21-32
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• 2009

Coastal sand dune area is the important ecosystem as an ecotone which located between coastal area and terrestrial area. Moreover, it is very complicate landscape that have geomorphological interaction between erosion and accumulation of sand. Therefore, it is necessary to understand the sand dune ecosystem in view point of landscape scale including background landscape affecting origin of sand dune. Landscape ecological approach in the complicate ecosystem already started in developed countries, and it is applied to land management and biodiversity conservation strategies even in national scale. In this paper, landscape ecological analysis using landscape pattern analysis was carried out on 7 study areas (Yellow Sea : Hakampo and Doksan, South Sea : Namyeol and Balpo, East Sea : Hosan, Hupo and Goraebul) in Korean coastal sand dune ecosystem. Landscape elements were composed by 9 elements in these study areas. Major background landscape elements was the forest land and agricultural field. Namyeol (S06) has larger patch landscape compare to other areas. In patch shape indices, Hupo (E10) shows more complicate patch shapes. The high landscape heterogeneity showed in the Doksan sand dune area and that of Hosan. It shows that these areas were composed by various patch types. However, using landscape indices have to use very carefully because several variables have influence to the result such as scale and spatial pattern of study areas. Although landscape analysis through landscape indices shows sometimes difficult to explain the ecosystem, landscape scale approach on ecosystem assessment still useful to interpret in ecological process in large range of habitat.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.7 no.1
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• pp.57-69
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• 1995

The development of a finite difference model for cross-shore sediment transport prediction in the surf tone due to the storm surge event is presented in this paper. Using the inhomogeneous diffusion equation with moving boundaries. the present numerical model is found to be robust and efficient and does not possess a number of restrictions imposed in Kriebel and Dean's(1985) numerical model. Our numerical model is validated through comparison with the analytical solution. the data of a large-scale experiment and the field data of Hurricane Eloise. The Present model if able to predict the averaged volumetric erosion rate of a beach due to the time-varying real storm surge hydrographs and satisfies the conservation of sediment between eroded volume in the onshore region and deposited volume in the offshore region. In addition. the present model is able to reasonably predict the recession of a beach with wide berm and dune. and can describe the change of a breaking point by the offshore deposition. From the sensitivity analysis or the present numerical model with various input parameters, it is concluded that the present numerical model is able to analyze the beach change in a reliable manner including the effects of different sizes of sediments.

• Korean Institute of Interior Design Journal
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• v.18 no.6
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• pp.221-228
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• 2009

Recently severity of ecological adaptation and climatic change due to global warming grows larger. According to the fourth report of IPCC in 2007, emission quantity of the earth greenhouse gas(GHGs) generated by activity of mankind increased with 80% since 1970. And it is forecasted that worldwide greenhouse gas will be increased with 25~90%(corresponding to $CO_2$) between 2000 and 2030. This increment of greenhouse gas($CO_2$) is expected to raise average temperature of the earth with the maximum $6.4^{\circ}C$, and sea surface with 59cm in 2090. Like this, destruction of environment by greenhouse gas is regarded as universal problem threatening the existence, not only the problem of one nation. Consequently, systematic correspondence to the global warming at the aspect of energy consumption is also needed in Korea. From the analysis result of 'Statistics of Energy Consumption' published by Green Korea in 2007, energy consumption increment of domestic universities was higher as many as 3.7 times than 22.5% of the whole energy consumption increment in our country. This says to be the direct example which shows that universities are huge sources of greenhouse gas emission. New constructing and enlarging buildings of each universities within campus are the most major reason for such a large increment of energy consumption in universities. The opinion that the possibility of causing energy waste and efficiency reduction is raised by increased buildings of universities has been propounded. That is, universities should make concrete goal and the plan for reducing emission of green house gas against climatic change, and should practice. Accordingly, there is the meaning that 2 aspects of environment-friendly design characteristics, that is application of energy utilizing technology, material usage of energy efficiency-side and environment-side, and introduction of natural element in the environmental aspect, were analyzed for facilities of university campus designed in environment-friendly point of view from initial stage of plan, and direction of environment-friendly design of university facilities in the future was groped in order to grasp environment-friendly design tendency of internal and external University facilities based on this analysis of this paper.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.12
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• pp.176-183
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• 2009

Distributed generation(DG) of combined cooling, heat, and power(CCHP)has been gaining momentum in recent year as efficient, secure alternative for meeting increasing energy demands. This paper presents the energy performance of microturbine CCHP system equipped with an absorption chiller by modelling it in hospital building. The orders of study were as following. 1)The list and schedule of energy consumption equipment in hospital were examined such as heating and cooling machine, light etc. 2) Annual report of energy usage and monitoring data were examined as heating, cooling, DHW, lighting, etc. 3) The weather data in 2007 was used for simulation and was arranged by meteorological office data in Daejeon. 4) Reference simulation model was built by comparison of real energy consumption and simulation result by TRNSYS and ESP-r. The energy consumption pattern of building were analyzed by simulation model and energy reduction rate were calculated over the cogeneration. As a result of this study, power generation efficiency of turbine was about 30[%] after installing micro gas turbine and lighting energy as well as total electricity consumption can be reduced by 40[%]. If electricity energy and waste heat in turbine are used, 56[%] of heating energy and 67[%] of cooling energy can be reduced respectively, and total system efficiency can be increased up to 70[%].