• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.12
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• pp.1627-1636
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• 2014

In real-time electricity price environment, the energy management system can provide the significant advantage to the residential, commercial and industrial customers since it can reduce the electricity charge by controlling the load operation effectively in response to time-varying price. However, the earlier studies for load management mainly focus on the residential and commercial customers except for the industrial customers because most of load operations in industrial sector are intimately related with production schedule. So, it is possible that the inappropriate control of loads in industrial sector causes huge economic loss. In this paper, therefore, we propose load control algorithm for factory energy management system(F-EMS) to achieve not only minimizing the electricity charges but also maintaining production efficiency by considering characteristics of load operation and production schedule. Considering characteristics of load operation and production schedule, the proposed load control algorithm can reflect the various characteristics of specific industrial customer and control their loads within the range that the production efficiency is maintained. Simulation results show that the proposed load control algorithm for F-EMS leads to significant reduction in the electricity charges and peak power in industrial sector.

• Journal of Hydrogen and New Energy
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• v.22 no.6
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• pp.772-779
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• 2011

New type of syngas generator based on the partial oxidation of biogas in volumetric permeable matrix reformers was suggested as an effective, adaptable and relatively simple way of syngas and hydrogen production for various low-scale applications. The use of biogas as an energy source reduces the chance of possible emission of two greenhouse gases, $CH_4$ and $CO_2$, into the atmosphere at the same time. Its nature of being a reproducible energy source makes its use even more attractive. Parametric screening studies were achieved as air ratio, biogas component ratio, input gas temperature, Steam/Carbon ratio. As the air ratio was low, the production of the hydrogen and carbon monoxide increased in the condition that 3D matrix reformer maintains the stable driving. As it was the simulation biogas in which the carbon dioxide content is high, the flammable range became narrow. And the flammable range was extended if the injected gas was preheated. The stable driving was possible in the low air ratio. The amount of hydrogen production was increased as S/C ratio increased.

• Journal of Hydrogen and New Energy
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• v.22 no.5
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• pp.741-748
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• 2011

Hydrogen is clean and renewable, and recognized as a very promising energy resource to solve both depletion of petroleum and environmental problems caused by the use of fossil fuels. Extensive researches have been performed worldwide on the production technologies of hydrogen. In this paper, the technology trend of photo-electrochemical (PEC) hydrogen production was scrutinized based on the patent and paper analysis. Open/registered patents of US, JP, EP, and KR and SCI Journals related to the PEC hydrogen production technology between 1996~2010 were reviewed. Patents and papers were gathered by using the key-words searching method and filtered by desirable filtering criteria. The technology trend was discussed by classifying each patent and paper based on the publishing year, country, and organization, and analyzing the core patents and papers.

• Environmental and Resource Economics Review
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• v.20 no.1
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• pp.33-60
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• 2011

The purpose of the article is to compare the impacts of energy efficiency and economic growth for energy demand through production frontier approach in OECD countries. We compared the traditional energy intensity with energy efficiencies of production frontier approach, slack efficiency on the frontier, and estimated elasticity of energy demand for GDP growth. First, the energy intensity has a low relationship with energy efficiency by radial approach, but has constant correlations with slack energy efficiency, slack-adjusted efficiency by non-radial approach, and energy efficiency by horizon approach. If we measure energy efficiency only with energy elasticity, it may make a mistake. Especially the energy efficiency by radial approach has a tendency to overestimate most OECD countries. Second, as many countries have excess energy consumption of 17.3% even on the points of the frontier, reduction of energy consumption is necessary in addition. Third, the average energy elasticity of OECD countries is 1.1 close to elasticity 1. There exists the difference of elasticity among countries and the energy demands are also high in countries with high elasticity.

• Journal of Hydrogen and New Energy
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• v.17 no.3
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• pp.286-292
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• 2006

Chlamydomonas reinhardtii is a green algae that can use light energy and water to produce hydrogen under anaerobic condition. This work reports the effect of limiting factors on hydrogen production in sulfur deprived anaerobic C. reinhardtii culture. In order to confirm the relationship between hydrogen production and limiting factors such as residual PSII activity and endogenic substrate degradation, the increase in chlorophyll concentration and the decrease in starch concentration was investigated during sulfur deprivation. The overall hydrogen production increased depending on cell density in range of $0.4{\sim}0.96\;g$ DCW/l. At this time, the increase in chlorophyll concentration during 24 h after sulfur deprivation increased in proportion to hydrogen production, however, the decrease in starch concentration was not proportional to that. Therefore, hydrogen production under sulfur deprivation using green alga was closely associated with the residual PSII activity than the endogenic substrate degradation.

• Journal of information and communication convergence engineering
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• v.3 no.2
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• pp.63-66
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• 2005

In 2000, the EU set up an energy policy related renewables use for electricity demand up to $22\%$ on the purpose of preventing energy exhaustion and world climate exchange. Technology development and energy production policy on coal, oil and natural gas focus on how to minimize their environmental effects since the world energy system will continue to be dominated by fossil fuels with almost $90\%$ of total energy supply in 2030. In the long run, the EU drives expansion policy of the renewable energy. If related policies and programs will show successful operation in the near future and will be resulted in increase of budget, we could expect the possibility of expansion of renewable energy market in Korea in the future.

• Korean System Dynamics Review
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• v.10 no.3
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• pp.105-124
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• 2009

The situation of the global food markets has been being rapidly restructured and entering on a new phase by new dynamic and driving forces. The factors such as economic growth and income increase, high energy price, globalization, urbanization, and global climate change are transforming patterns of food consumption, production, and markets. The prices and markets of world food and energy are getting increasingly linked each other. Food and fuel are the global dilemma issues associated with the risk of diverting farmland or of consuming cereals for biofuel production in detriment of the cereals supply to the global food markets. An estimated 100 million tons of grain per year are being redirected from food to fuel. Therefore, the objectives of this study are as follows: Firstly, the study examines situations of the world food and energy resources, analyzes the trends of prices of the crude oil and biofuel, and formulates the food-energy links mechanism. Secondly, the study builds a simulation model, based on system dynamics approach, for not only analyzing the global cereals market and energy market but also forecasting the global production, consumption, and stock of those markets by 2030 in the future. The model of this study consists of four sectors, i.e., world population dynamics sector, global food market dynamics sector, global energy market dynamics sector, scenario sector of world economic growth and oil price.

• Journal of the Korean Solar Energy Society
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• v.36 no.2
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• pp.9-17
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• 2016

In order to examine how accurately the wind farm design software, WindPRO and Meteodyn WT, predict annual energy production (AEP), an investigation was carried out for Seongsan wind farm of Jeju Island. The one-year wind data was measured from wind sensors on met masts of Susan and Sumang which are 2.3 km, and 18 km away from Seongsan wind farm, respectively. MERRA (Modern-Era Retrospective Analysis for Research and Applications) reanalysis data was also analyzed for the same period of time. The real AEP data came from SCADA system of Seongsan wind farm, which was compare with AEP data predicted by WindPRO and Meteodyn WT. As a result, AEP predicted by Meteodyn WT was lower than that by WindPRO. The analysis of using wind data from met masts led to the conclusion that AEP prediction by CFD software, Meteodyn WT, is not always more accurate than that by linear program software, WindPRO. However, when MERRA reanalysis data was used, Meteodyn WT predicted AEP more accurately than WindPRO.

• Journal of Hydrogen and New Energy
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• v.20 no.5
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• pp.404-409
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• 2009

The present works were performed that titanium foil was anodized in various dilution ratios of seawater and distilled water with 10V external voltage applied, then annealed at $450^{\circ}C$ to obtain $TiO_2$ on the Ti substrate. The prepared samples were characterized by instruments (XRD, SEM, and photocurrent) and used to investigate rate of hydrogen production in photoelectrochemical cell as well as Cr(VI) reduction. As the results of experiments, the anodized $TiO_2$ in seawater electrolytes, which are ranged from 15 to 50 times dilution of seawater, was showed a relatively higher hydrogen production (ca. 97~110 umol/hr-$cm^2$) and Cr(VI) reduction (ca. 95% reduction).

• Journal of Hydrogen and New Energy
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• v.18 no.2
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• pp.151-156
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• 2007

Solar cell and nanofiltration membrane were utilized in a system of enzymatic hydrogen production through light-sensitized photoanode, which resembles photoelectrochemical(PEC) configuration. Solar cell uses no additional light energy to increase energy for electrons to reduce protons and for holes to oxidize water to oxygen, and nanofiltration membrane replaces a salt bridge successfully with increased ion transport capability. With this system configuration, optimized amount of enzyme(10.98 unit), and an anodized tubular $TiO_2$ electrode($5^{\circ}C$/1 hr in 0.5 wt% HF-$650^{\circ}C$/5 hr) hydrogen evolved at a rate of ca. $43\;{\mu}mol/(cm^2{\times}hr)$ in a cathodic compartment and oxygen generated at a rate of ca. $20\;{\mu}mol/(cm^2{\times}hr)$ in an anodic compartment. The stoichiometric evolution of gases indicated that water was splitted in the system.