• Membrane and Water Treatment
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• v.2 no.4
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• pp.225-237
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• 2011

In this study, response of reversibility of membrane flux during chemically enhanced backwash (CEB) to changes in filtration time, filtration flux and coagulant concentration dosing during ultrafiltration (UF) process was investigated using a regression model. The model was developed via empirical modelling approach using response surface methodology. In developing the model, statistically designed UF experiments were conducted and the results compared with the model output. The results showed that the performance of CEB, evaluated in terms of the reversibility of the membrane flux, depends strongly on the changes in coagulant concentration dosage and the filtration flux. Also the response of the reversibility of membrane flux during CEB is independent of the filtration time. The variance ratio, VR << $F_{value}$ and $R^2$ = 0.98 obtained from the cross-validation experiments indicate perfect agreement of the model output with experimental results and also testify to the validity and suitability of the model to predict reversibility of the membrane flux during CEB in UF operation.

• International conference on construction engineering and project management
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• 2005.10a
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• pp.824-829
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• 2005

This paper focuses on construction cost volatility for the purpose of private sector investment by use of a financial model with key indices of IRR and DSCR (Debt Service Coverage Ratio). A case project, 1,000 MW pumped storage hydropower plant, has shown that its financial impacts by cost volatility of underground works are less measured than interest rates impacts by interest rate of loans. Probabilistic analysis of costs under geotechnical conditions has been made by Indicator Kriging method. And, in the modeling of interest rates, geometric Brownian motion has been applied. Both of these impacts are measured on the same financial model.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.8
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• pp.1134-1139
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• 2014

Recently the need for renewable energy development is expanding due to the global climate change, the environmental issues and the limited fossil energy resources. Dependence of energy on overseas is high in Korea. To resolve the environmental problems and to improve the energy independence rate, the development of renewable energy is more required. The small hydro power, one of the renewable energy resources, has been developing and operating from a long time ago. If we are new developing a small hydro power with the use existing dams and reservoirs, we will design the length of inlet pipe and the diameter suitable for it. However, in case of using the existing water supply pipe which had been designed suitable for water service, the designer has to review and check that the pipe is suitable for operating a generator. In this paper, the design of small hydro power using the existing long pipe of water supply, we suggest the optimum way to reduce the water hammer in pipe which causes the unsteady flow during the load-shutdown of generator, the generator operation plan for the stable supply of water and the design factor of determining the generator capacity through the analysis between discharge and head-loss.

• Asia Pacific Journal of Business Review
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• v.3 no.1
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• pp.19-38
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• 2018

The energy intensity of Nepal is economically not worthy, lacks eco-friendly and importantly not sustainable, and almost four times the average global energy intensity. Considerable efforts have been exercised to reduce the energy gap yet, it is still much to achieve. Nation priority on energy sector was envisaged with promulgation of investment friendly rules and law in hydropower and renewable technology even though, could not harness the sufficient energy. In amid of this acute energy crisis, the government launched the Nepal Energy Efficiency Programme (NEEP) with technical assistance from German International Cooperation (GIZ). Energy Efficiency (EE) practice is the most cost-effective method to reduce the supply and demand gap, reduce on greenhouse gases and pollution, and deter on import of petroleum products which finally improves on trade imbalance. This paper had proposed a framework of energy management team to promote energy efficient technologies in residential consumer. The energy management teams study the past records of energy use pattern of consumers and suggest appropriate technology for energy saving options. The paper provides some reviews of energy efficiency initiatives undertaken by the concern regulatory body which highlights the current status. The comprehensive knowledge acquired through exploratory research is implemented in this paper to identify the various barriers that domestic consumer is experiencing towards the active participation in energy efficiency program launched by the Government of Nepal.

• The Southeast Asian review
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• v.28 no.1
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• pp.219-261
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• 2018

The conflicts among nations surrounding international rivers are intensifying as worldwide water shortage is getting worse. The Mekong River is a representative trans-boundary river in Southeast Asia shared by six countries, China, Myanmar, Thailand, Laos, Cambodia, and Vietnam. As the economy grows, hydroelectric power has become a major power supply source to meet the increasing power demand of the these countries. However, the construction of dams on the Mekong River is controversial because hydroelectric power in the river upstream has a negative impact not only on the whole river ecosystem but also on residents' life around downstream, in particular. In order to understand the controversy arising from international rivers, it is necessary to take into account different positions of countries sharing it. However, studies on the position of a specific country to Mekong hydropower have been conducted mainly focusing on China and Laos. Therefore, this study tried to study the position of Cambodian government which is located downstream of the Mekong River and is likely to bear costs rather than to gain benefits from hydroelectric power generation. What is the attitude of the Cambodian government to the hydroelectric development of the upper Mekong and what is the reason for that? The study confirmed the Cambodian government's support for dam construction on the Mekong River. It also figured out influential factors on the formation of such a position as follows: 1) economic asymmetry with China, 2) power dependency and geographical asymmetry in Laos, and 3) importance of hydroelectric power in Cambodia.

• Bulletin of the Korea Photovoltaic Society
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• v.6 no.1
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• pp.8-20
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• 2020

Nepal has huge potential of hydro and other renewable energy resources including solar energy. However, only 70% of the total population have access to electricity despite the long history of hydropower development in the country. Still more than 37% population in rural areas and around 73% population in Karnali Province, one of the least developed provinces, are living without access to electricity despite taking several initiatives and implementing various policies by government supporting electrification in off-grid rural areas. Government together with donors and private sector has extensively been promoting the off-grid solar photovoltaic (PV) echnology in un-electrified areas to increase electricity access. So far, more than 900,000 households in rural areas of Nepal are getting electricity from stand-alone solar PV systems. However, there are many challenges including financial, technical, institutional, and governance barriers in Nepal. This study based on extensive review of literatures and author's own long working experiences in renewable energy sector in Nepal, shares the best practices and lessons of off-grid solar PV for increasing access to electricity in rural areas of Nepal. This study suggests that flexible financial instruments, financial innovations, bundling of PV systems for concentrating energy loads, adopting standards process, local capacity building, and combination of technology, financing and institutional aspects are a key for enhancing effectiveness of solar PV technology in rural areas of Nepal.

• Journal of Distribution Science
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• v.14 no.8
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• pp.5-8
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• 2016

Purpose - With its considerable water resources, Lao People's Democratic Republic, hereafter Lao PDR, is considered to become the "battery" of the Southeast Asia region in the next 20 years. This paper explores the investment opportunity in the hydroelectricity development project in the Lao PDR. Research design, data, and methodology - Three significant investment factors including cultural factor, political factors, and economic factors are being literally analyzed. In fulfilling the purpose of this analysis, Num Theun 2 Power Company or NTPC, a current largest hydropower project in the country, is selected for an example of a mega investment project model in the country. Results - NTPC's investment plan, budgets, and current revenue and rate of return are briefly discussed throughout the paper. In addition, this paper also briefly compares and contrasts of the investment in the Lao PDR and investment in its neighboring Singapore who is considered one of the leading developed economies in the region. Conclusions - A recommendation is being proposed on the last section of this paper in the areas that Lao PDR may consider adopting in order to make its investment environment becomes more attractive to foreign investors.

• The KSFM Journal of Fluid Machinery
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• v.18 no.5
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• pp.19-25
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• 2015

As a core component of a hydropower station, hydro turbines play a vital role in the integration of a power station. Research on the technology of hydro turbine is continuously increasing with the development of water electricity. On the basis of one-dimensional loss analysis, for three-dimension design, there are a lot of dimension of the internal flow passage shapes that are determined by experience. Therefore, the effect of the internal flow passage shapes on the performance and internal flow characteristics of a Francis hydro turbine model is investigated in this study. In this study, the small curvature of runner blade trailing edge shape is good for improving the efficiency of Francis turbine. The straight stay vane leading edge is good for suppressing the secondary flow. Moreover, suitable tongue passage shape and stay vane number improve the performance of the turbine considerably.

• New & Renewable Energy
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• v.10 no.2
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• pp.5-11
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• 2014

Squirrel cage induction motor is the main driving system of industrial field and familiar with its use in a large variety of applications. The structure and operating characteristics of induction generator is almost identical to induction motor, but the induction generator part is used restrictively from hydropower power and wind power development etc. Recently induction generator is commonly used for micro & small hydro power applications due to its simplicity, reliability, low cost and robustness. Input and output of induction motor has turned against at the induction generator operation. Rotation speed of induction generator is small faster than synchronous speed of induction motor. As output of induction machines increases with the increasement of speed, so loss is same. Actually, generator efficiency is lower than motor at this condition. If induction generator is connected with mechanical load such as increaser, total efficiency is decreased. Consequently the quality in compliance with an induction motor parameter applying like that in the generator is a possibility of having the error of some. In this paper, we analyzed that input, output, torque and efficiency of induction machine is different from each other above and below synchronous speed.

• Transactions of the Korean hydrogen and new energy society
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• v.15 no.4
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• pp.324-332
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• 2004

According to the rapid depletion of the fossil fuels, the electricity and hydrogen will gradually take charge of the future energy supply. Especially, in order to control the supply and demand of electricity, energy storage medium is necessary and this could be solved by the combination of water electrolysis and fuel cell. Although electricity can be generated from such alternative energies as hydropower, nuclear, solar, and wind-power resources, alternative energy storage medium is also required since regenerative energies, solar and wind-powers, are intermittent energy resources. In this regard, hydrogen production from water electrolysis was recognized as a superb method for electricity storage. In this work, the current development and economic status of alkaline, solid polymer, and high temperature electrolysis were reviewed, and then the practical use of water electrolysis technology were discussed.