• Journal of the Korean Solar Energy Society
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• v.30 no.2
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• pp.81-86
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• 2010

Since the solar energy resource is the main input for sizing any solar photovoltaic system and solar thermal power system, it is essential to utilize the solar radiation data as a application and development of solar energy system increase. It will be necessary to understand and evaluate the insolation data. The Korea Institute of Energy Research(KIER) has begun collecting horizontal global insolation data since May, 1982 and direct normal insolation data since December 1992 at 16 different locations in Korea. Because of a poor reliability of existing data, KIER's new data will be extensively used by solar energy system users as well as by research institutes. From the results, the yearly averaged horizontal global insolation was turned out 3.60kWh/$m^2$/day and a significant difference of horizontal global insolation is observed between 1982~1990 and 1991~1999, 2000~2008 through 16 different cities in Korea.

• Journal of Hydrogen and New Energy
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• v.27 no.4
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• pp.431-440
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• 2016

Electric or hydrogen energy source is expected to solve a various issues including energy security and exhaust pollution. However, it is required a lot of time and a variety of development to apply for commercialization. Therefore, it is needed to translation fuels between the future and the present. DME (Dimethyl Ether) can play a reduce exhaust emission from medium- to heavy-duty engines that are mostly used in commercial sector. It have applied to the DME fuel as a various alternative fuel including power generation in many countries. Especially, it is necessary to secure the energy of energy-poor areas that are widely distributed around the world. And Korea also has the energy-poor areas due to geographical characteristics. These areas has been covered by their own energy through some small diesel generators, diesel boiler etc. If DME fuels are supplied in new demand such as rural sector with energy poor area, DME fuel will be available in the wider sector. In this study, it investigated performance and emission characteristics of agricultural generator and air heater using DME fuel. So the existing equipment of generator and air heater was modified to apply DME fuel. And combustion characteristics and properties of exhaust gas according to the contents of the DME fuel were evaluated. DME fuel showed a potential application in agricultural generator and air heater.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.39.2-39.2
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• 2011

The new and renewable energy today has a great interest in all countries around the world. In special it has need more limit of the fossil fuel that needs of low carbon emission among the social necessary conditions. Recently, the high-rise building demand the structural safety, the economic feasibility and the functional design. The high-rise building spends enormous energy and it satisfied the design in solving energy requirements. The requirements of energy for the building depends on the partly form wind energy due to the cladding of the building that came from the surroundings of the high-rise building. In this study of the wind energy, the cladding of the building was assessed a tentative study. The wind energy obtains from several small wind powers that came from the building or the surrounding of the building. In making a cladding the wind energy forms with wind pressure by means of energy transformation methods. The assessment for the building cladding was surrounded of wind speed and wind pressure that was carried out as a result of numerical simulation of wind environment and wind pressure which is coefficient around the high-rise building with the computational fluid dynamics. In case of the obtained wind energy from the pressure of the building cladding was estimated by the simulation of CFD of the building. The wind energy at this case was calculated by energy transform methods: the wind pressure coefficients were obtained from the simulated model for wind environment using CFD as follow. The concept for the factor of $E_f$ was suggested in this study. $$C_p=\frac{P_{surface}}{0.5{\rho}V^{2ref}}$$ $$E_c=C_p{\cdot}E_f$$ Where $C_p$ is wind pressure coefficient from CFD, $E_f$ means energy transformation parameter from the principle of the conservation of energy and $E_c$ means energy from the building cladding. The other wind energy that is $E_p$ was assessed by wind power on the building or building surroundings. In this case the small wind power system was carried out for wind energy on the place with the building and it was simulated by computational fluid dynamics. Therefore the total wind energy in the building was calculated as the follows. $$E=E_c+E_p$$ The energy transformation, which is $E_f$ will need more research and estimation for various wind situation of the building. It is necessary for the assessment to make a comparative study about the wind tunnel test or full scale test.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.1
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• pp.70-76
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• 2017

The pollution problem of fossil energy sources has caused the development of green energy harvesting systems. Piezoelectric energy harvesting technology has been developed under those external environmental factors. A piezoelectric energy harvester can be defined as a device which transforms mechanical vibration or impact energy into electrical energy. Most researches have focused on bender structures. However, these have a limitation on energy efficiency because of the small effective electromechanical coupling factor, around 10%. Therefore, we should look for a new design for energy harvesting. A cymbal energy harvester can be a good candidate for the high-power energy harvester because it uses a high amplification mechanism using endcaps while keeping a higher electromechanical coupling factor. In this research, we focused on energy efficiency improvements of the cymbal energy harvester by changing the polarization direction, because the electromechanical coupling factor of the k33 mode and the k15 mode is larger than that of the k31 mode. Theoretically, we checked the cymbal harvester with radial polarization and it could obtain 6 times larger energy than that with the k31 direction polarization. Furthermore, we verified the theoretical expectation using the finite element method program. Consequently, we could expect a more efficient cymbal harvester with the radial polarization by comparing two polarization directions.

• New & Renewable Energy
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• v.20 no.1
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• pp.95-101
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• 2024

Since 1990, the Renewable Big Data Research Lab at the Korea Institute of Energy Technology has been observing solar radiation at 16 sites across South Korea. Serving as the National Reference Standard Data Center for Renewable Energy since 2012, it produces essential data for the sector. By 2020, it standardized meteorological year data from 22 sites. Despite user demand for data from approximately 260 sites, equivalent to South Korea's municipalities, this need exceeds the capability of measurement-based data. In response, our team developed a method to derive solar radiation data from satellite images, covering South Korea in 400,000 grids of 500 m × 500 m each. Utilizing satellite-derived data and ERA5-Land reanalysis data from the European Centre for Medium-Range Weather Forecasts (ECMWF), we produced standard meteorological year data for 1,000 sites. Our research also focused on data measurement traceability and uncertainty estimation, ensuring the reliability of our model data and the traceability of existing measurement-based data.

• Journal of Internet Computing and Services
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• v.22 no.6
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• pp.17-24
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• 2021

The use of renewable energy sources for power generation has been steadily increasing. Power generation using renewable energy has the advantage of not generating carbon but has the disadvantage of high volatility depending on the weather. This volatility makes stable power supply difficult. Curtailment is occurring to address volatility. Various facilities are operated together to solve the loss caused by the curtailment. The existing SCADA must be modified for turbine control reflecting the conditions of various facilities. However, since it is difficult to modify SCADA, a modular control system is required. In this study, we propose Modular Control System Based on Closed-Loop Control for Wind Farms. Since the control logic can be changed without modifying SCADA, it is easy to respond to changes. The developed modular control system was evaluated as a lab test and confirmed to operate smoothly. Through future research, the experiment will be conducted by applying a modular control system to the actual wind farm.

• Journal of Information Technology Services
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• v.6 no.1
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• pp.141-149
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• 2007

Sensor node's mobility brings new challenges to data dissemination in large sensor networks. Frequent location updates of sensor nodes can lead to both excessive drain of sensor's limited battery supply and increased collisions in wireless transmissions. Conventional studies for routing protocols in wireless sensor networks are not enough to cover energy consumption and migration of sensor nodes. This study proposes a dynamic routing protocol based on the SPIN considering energy consumption and the migration, and also shows the effectiveness of the proposed routing protocol.

• Journal of the Korean Solar Energy Society
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• v.23 no.3
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• pp.63-71
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• 2003

According to the recent report, the lighting energy consumption of commercial buildings reaches to $30%\sim40%$ of the total energy consumption. It is more than that of cooling & heating energy consumption and it is the major target of energy-saving policy. It is obvious that they are interested in natural lighting device such as Light-shelf for the purpose of raising the lighting energy-saving efficiency. In most of highly developed countries, a thorough study on Light-shelf makes it possible to propose a practical plan while at home there leaves much to be desired to study a guiding principle of optimum plan in spite of its efficiency based on experiments using scale4 model and analysis of simulation. Aiming at making an optimum plan of Light-shelf suitable for the domestic situation, this study is worked by experiments using light-shelf and analysis of variables using illumination program. The experiments is to analyse the efficiency of Light-shelf on condition of the sky and the analysis is to make the simulation using illumination program. This study is composed of 1) the analysis of light with some variables such as presence of light-shelf and degree of angle using 1/2 scaled model 2) making the simulation using Lightscape, illumination program, In brief, concerning presence of light-shelf, it causes little difference in its efficiency in the overcast sky, whereas it decreases an illuminance of window side and provides inner side with the light, which decreases the ratio of the maximum to the minimum inner illuminance and makes the inner of illuminance to range evenly in the clear sky. On degree of angle, as the daylight increases in proportion of degree of angle, the ratio of the maximum to the minimum inner illuminance decreases, which makes it possible to increase the proportion of inner daylight.

• 한국태양에너지학회:학술대회논문집
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• 2008.11a
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• pp.112-119
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• 2008

In order to ensure building energy management at an appropriate level continuously, it is necessary to define clearly service work of energy management and to suggest evaluation index whether energy management in buildings is fit and improvement is needed or not. But, evaluation index of energy management level in buildings is not suggested yet in Korea. So, the purpose of this paper is to suggest evaluation index of energy management level in buildings, investigate the present state of Korean buildings and evaluate energy management levels. As a result of surveys of evaluation index of energy management, it is found that portion of level 1, which is the best level, is higher than any other level, level 2, level 3. And, throughout analysis, it is found that as total floor area is larger, evaluation index of energy management level is better, and, in order to increase energy management level, first of all, there is necessary for building's users to change understanding about energy saving and make a reform of national policy of energy management in buildings. Because there is rich relationship between items among evaluation index of this stuff and result value of evaluation index, evaluation index of energy management suggested in this study is available to evaluate energy management level in buildings.

• Journal of Communications and Networks
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• v.12 no.2
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• pp.103-113
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• 2010

In this paper, a tradeoff between the total energy consumption-per-bit and the end-to-end rate under spatial reuse in wireless multi-hop network is developed and analyzed. The end-to-end rate of the network is the number of information bits transmitted (end-to-end) per channel use by any node in the network that is forwarding the data. In order to increase the bandwidth efficiency, spatial reuse is considered whereby simultaneous relay transmissions are allowed provided there is a minimum separation between such transmitters. The total energy consumption-per-bit includes the energy transmitted and the energy consumed by the receiver to process (demodulate and decoder) the received signal. The total energy consumption-per-bit is normalized by the distance between a source-destination pair in order to be consistent with a direct (single-hop) communication network. Lower bounds on this energy-bandwidth tradeoff are analyzed using convex optimization methods. For a given location of relays, it is shown that the total energy consumption-per-bit is minimized by optimally selecting the end-to-end rate. It is also demonstrated that spatial reuse can improve the bandwidth efficiency for a given total energy consumption-per-bit. However, at the rate that minimizes the total energy consumption-per-bit, spatial reuse does not provide lower energy consumption-per-bit compared to the case without spatial reuse. This is because spatial reuse requires more receiver energy consumption at a given end-to-end rate. Such degraded energy efficiency can be compensated by varying the minimum separation of hops between simultaneous transmitters. In the case of equi-spaced relays, analytical results for the energy-bandwidth tradeoff are provided and it is shown that the minimum energy consumption-per-bit decreases linearly with the end-to-end distance.