• Solar Energy
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• v.13 no.2_3
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• pp.45-52
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• 1993

The benefits of thermal stratification in sensible heat storage were investigated for residential solar applications. The effect of increased thermal useful efficiency of hot water stored in an actual storage tank due to stratification has been discussed and illustrated through experimental data and computer simulation, which were taken by changing dynamic and geometric parameters. When the flow rate was 8 liter/min and ${\Delta}T=40^{\circ}C$ was $40^{\circ}C$, the useful efficiency(${\eta}_u$) was about 90% in case of using a distributor, but not using a distributor the useful efficiency(${\eta}_u$) was about 82%. So these kinds of distributor would be recommendable for a hot water storage system and residential solar energy application to increase useful efficiency(${\eta}_u$). In the case of the uniform circular distributor, when the flow rate was 8 liter/min partial mixing was decreased and a stable stratification was obtained. Furthermore, if the distrbutor was manufactured so that the flow is to be the same from all perforations in order to enhance stratification, it might be predicted that further stable stratification and higher useful efficiency(${\eta}_u$) are obtainable.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.12
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• pp.1792-1797
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• 2013

Recently, due to the excessive use of fossil fuels, many studies about the fossil fuels such as solar and fuel cell energy source are progressing. Fuel cell system has high energy conversion efficiency. Also, fuel cell system is environmentally friendly system because the carbon emission is almost not occur. Therefore, the fuel cell system is considered as the core technology of in the fields of the future energy and environmental. Fuel cell system has an effect on distribution power system because another power source of other than large power plants. So, fuel cell system can be reason of power quality in the power system. In this paper, we constructed the system for an assessment on Islanding. The system is composed with power source, Impedance coordination load and linear load, fuel cell system. we are performed assessment on voltage and power quality in customer and the distributed power system during the Islanding of residential fuel cell system. In addition, no change in the impedance of power system, we made a islanding condition only using the actual load, As a variation of generation and load current under islanding, an analysis results based on assessment system showed that the power qualities of distribution system became more aggravation as effect of voltage sag and voltage swell phenomena.

• Advances in environmental research
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• v.6 no.2
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• pp.139-146
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• 2017

The purpose of this study was to determine the present air pollutant concentrations and predicted levels for next 30 years in urban environment of Karachi city. For that, a total of fifty measurements were made for each twenty selected locations of the city. The locations were selected on the basis of land use pattern such as residential, commercial, industrial settlements, open areas, congested traffic and low traffic areas for investigation of air pollutants variability and intensity. The measurements were taken continuously for six months period using PM Meter, Model AEROCET 531 and Ambient Air Quality Meter, Model AAQ 7545. The concentration of air pollutants were found higher at Al Asif Square and Maripur Road due to higher intensity of traffic and at Korangi Crossing because of industrial areas. The level of pollutants was lower at Sea View owing to lower traffic congestion and transportation of pollutants by sea breezes.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.26 no.5
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• pp.212-217
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• 2014

Recently, the use of renewable energy has been increased due to growing concern on the energy-saving at buildings and the reduction of $CO_2$ emission. In the field of architecture, to reduce the energy consumption of heating, cooling and hot water supply, heat pump systems with renewable energy has been developed and used in various applications. However, there have been many of researches on the large-scale commercial heat pump systems, but the research and the field application of a compact heat pump system is rare. Therefore, in order to develop the compact heat pump for the small-scale residential building, this study conducted the performance test and feasibility study for a hybrid heat pump using the heat source of air, solar and ground. In the results of experiments through a trial product, the average COP of cooling mode with ground heat source was 4.75, and it of heating mode was 4.03. Furthermore, the average COP of cooling mode with air heat source was 2.60, and it of heating mode was 2.92. Finally, payback period of the system was calculated as 9.2 years.

• International Journal of High-Rise Buildings
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• v.6 no.2
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• pp.113-129
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• 2017

This paper presents the initial findings of a ground-breaking two-year CTBUH-funded research project investigating the real environmental and social sustainability of people's lifestyles in a number of high-rise residential towers in downtown Chicago, and a comparable number of low rise homes in suburban Oak Park, Chicago - based on actual energy bills and other real data. The study is ground-breaking because, to date, similar studies have been mostly based on very large data sets of generalized data regarding whole-city energy consumption, or large-scale transport patterns, which often misses important nuances. This study has thus prioritized quality of real data (based on around 250 households in both high rise and low rise case studies), over quantity. In both urban and suburban cases, the following factors have been assessed: (i) home operational energy use, (ii) embodied energy of the dwelling, (iii) home water consumption, (iv) mobility and transport movements, (v) urban/suburban Infrastructure, and (vi) quality of life. The full results of this seminal study will be published in the form of a CTBUH Research Report publication in 2017. Presented below is an overview of the initial (and, currently, unverified) findings of the research, together with the limitations of the study that should be taken into account, as well as future plans for developing this important pilot study.

• Wind and Structures
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• v.29 no.1
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• pp.15-32
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• 2019

Much advancement has been made in wind power due to modern technological developments. The wind energy technology is the world's fastest-growing energy option. More power can be generated from wind energy by the use of new design and techniques of wind energy machines. The geographical areas with suitable wind speed are more favorable and preferred for wind power deployment over other sources of energy generation. Today's wind turbines are mainly the horizontal axis wind turbines (HAWTs) and vertical axis wind turbines (VAWTs). HAWTs are commercially available in various sizes starting from a few kilowatts to multi-megawatts and are suitable for almost all applications, including both onshore and offshore deployment. On the other hand, VAWTs finds their places in small and residential wind applications. The objective of the present work is to review the technological development, available sizes, efficiencies, structural types, and structural stability of VAWTs. Structural stability and efficiencies of the VAWTS are found to be dependent on the structural shape and size.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.1
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• pp.117-122
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• 2010

The solar cells and fuel cells power are being encouraged to reduce the environmental pollution and combat the global warming. And the electric generation hybrid system is usually more reliable and less costly than the systems that use a single source of energy. HOMER provides a platform to design and simulate the power system and then to choose the optimization results. Based on the electricity demand conditions during a year, this paper simulates with the HOMER and performs the monthly average electrical production and the most feasible economical case includes the net present costs and the annualized costs of the hybrid system components.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.310-312
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• 2000

This paper presents database for electricity demand-side management. Demand-Side Management(DSM) refers to programs that influence the usage of energy for improved economic efficiency and reduced environmental impact DSM can be looked upon as a tool for energy utilities to find resources on the demand side instead of on the supply side, or as a more general tool for society to better use and distribute scarce resources. In this paper, we construct the database for electricity demand-side management and apply it to residential and commercial sector.

• KIEAE Journal
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• v.1 no.1
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• pp.17-26
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• 2001

The purpose of this study is to develop an underground Building. Population tends to concentrate in large cities. In result, the cities lacks housings. Underground space may be a attractive space by being able to gain alternative energy and get a cheap site, protect environment at the same time. The earth or ground is a useful medium for a long-term heat source and storage of it's heat. Also the underground space has the status of stabilization, the lower heating load and the similar heat transfer coefficient of the inside wall surface comparing to that of residential space. Utilization of underground space has many advantages to cope with lack of building sites and energy conservation, etc. As a result, it is expected to provide a useful information for the practical use of Underground building.

• Journal of Environmental Impact Assessment
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• v.19 no.4
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• pp.397-407
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• 2010

The increase of the solar reradiation from urban areas relative to suburban due to urbanization heats up the air temperature in urban areas and this is called the urban heat island (UHI) effect. This UHI effect has a positive relationship with the degree of urbanization. Through the studies on UHI using the satellite imagery, the effect of the surface heat radiation was observed by verifying the relationship between the air temperature and the land cover types (surface materials such as urban, vegetation, etc.). In this study, however, the surface temperature distribution was studied in terms of land use types for Seoul. Using land use types, the surface temperature in urban areas such as residential, industrial, and commercial areas in Yeongdeungpo, highly packed with industrial and residential buildings, was maximum $6^{\circ}C$ higher than in the bare ground, which indicated that the surface temperature reflected the pattern of the human-consumed energy on the areas and showed that one of the important causes influencing the air temperature except the surface heat reradiation by the sun is the anthropogenic heat. Also, the effect due to the restoration of the Chunggae stream on UHI was investigated. The average surface temperature for the Chunggae stream was reduced about $0.4^{\circ}C$ after restoration. Considering that each satellite image pixel includes mixture of several materials such as concrete and asphalt, the average surface temperature might be much lower locally reducing UHI near the stream.