• Journal of the Korean Solar Energy Society
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• v.33 no.5
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• pp.18-23
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• 2013

This paper presents a simple but valid loss calculation method of grid-connected photovoltaic system based on normalized yield model. The proposed method can be represented as a quantitative value for five losses and performance of grid-connected photovoltaic system with three years monitored data. These results will indicate that it is useful to investigate various loss factors causing the performance obstruction, enhance the lifetime yield for changing meteorological conditions, and determine the optimal design and performance improvement of grid-connected photovoltaic system.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.584-587
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• 2006

An energy generating greenhouse based on fluoropolymer envelope and fresnel lens is proposed. The outstanding properties of the fluoropolymer films make them very suitable for large scale solar applications. Extremely high optical transmission over the whole solar spectrum, combined with mechanical strength, and durability allows us to design a highly optimized greenhouses for both plant growing and energy generation. Systems such as photovoltaic triple junction cells are especially attractive since they have up to 35% efficiency with much less cell material when the sun beam is focused with concentrators such as fresnel lenses. Cooling such devices will enhance the efficiency and provide useful thermal energy that could be further utilized for various applications depending on the local demands. This article introduces the basic ideas and principles of the energy generating greenhouses as a first step towards the actual deployment of such systems under Korean environment.

• 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 Advanced Marine Engineering and Technology
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• v.23 no.6
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• pp.794-805
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• 1999

Pneumatic cushioning cylinders are commonly employed for vibration and shock control. A mathematical simulation model of a double acting pneumatic cushioning cylinder designed to absorb shock loads is presented which is based on the following assumptions; ideal equation of state isentropic flow through a port conservation of mass polytropic thermodynamics single degree of freedom piston dynamics and energy equivalent linear damping. These differential equation can be solved through numerical integration using the fourth order Runge-Kutta method. An experimental study was conducted to validate the results obtained by the numerical integra-tion technique. Simulated results show good agreement with experimental data. The computer simulation model presented here has been extremely useful not only in understanding the has been extremely useful not only in understanding the basic cushioning but also in evaluating different designs.

• Journal of Mechanical Science and Technology
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• v.15 no.3
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• pp.357-365
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• 2001

The aim of this paper is to perform the experiment and the numerical simulation for investigating the heat transfer in a regenerator system with ceramic honeycomb and to suggest a useful correlation for optimization of the regenerator system. For achieving this, the effects of some parameters were investigated, e. g., switching time, cell size and length of honeycomb on the mean temperature efficiency. The measured temperatures by R-type thermocouples were compared with the predictions by means of the commercial package, STAR-CD. A useful correlation for thermal efficiency was newly proposed as a function of the normalized switching time, defined in terms of switching time, cell size and length of honeycomb. The results showed that the thermal efficiency is above 90% and the normalized heat exchange rate is higher than 80% when the normalized switching time is less than 1000.

• Journal of environmental and Sanitary engineering
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• v.9 no.2
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• pp.88-100
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• 1994

A study on the recovery of useful components from waste tire. This study was carried out investigate the recovery of fuel oil condensed from gases formed in the pyrolysis of waste tire. Energy to require the pyrolysis of waste tire was used the heat that was produced by the combustion of the gases from the pyrolysis of waste tire itself. The results are as follows; 1. Energy to require forming the fuel oil by the pyrolysis of waste tire was used only 1/6 quantities of waste tire for forming fuel oil. 2. The formed fuel oil were light oil, Kerosene and gasoline 3. The pollutants of combustion gas of patronizable gases was lower than standard Value.

• Particle and aerosol research
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• v.9 no.3
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• pp.139-147
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• 2013

The performances of indoor air cleaners including particle cleaning capacity and collection efficiency are usually tested at the condition of the maximum air flow rate of the air cleaners. However, the power consumption of the air cleaners is highly dependent on the air flow rate of the individual air cleaners. Therefore, there seems to be an optimized air flow rate for the air cleaning capacity considering power consumption. In this study, clean air delivery rate(or standard useful area as suggested room size) and power consumption have been investigated for different maximum air flow rates of 15 air cleaners and then compared those for different air flow rate modes of the individual 5 air cleaners selected from the 15 cleaners. For the maximum air flow rate conditions of 15 air cleansers, the power consumption per unit area was less related to the maximum air flow rate. However, for the different air flow rate modes of the selected 5 air cleaners, the lower power consumption per unit area was corresponding to the lower air flow rate mode of the individual air cleaners. When considering the operation time to the desired particle concentrations, there was an optimized one in the medium air flow rate modes for the individual air cleaners. Therefore, not only the maximum air flow rate but also lower air flow rates of individual air cleaners should be considered for estimating air cleaning capacity based on energy consumption per unit area.

• Journal of Radiation Industry
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• v.4 no.3
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• pp.277-283
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• 2010

Rape (Brassica napus L.) plants are one of the major oilseed crops. The main components of rapeseed are oil (35 to 47%) and protein (15 to 32%). For the biodiesel production, the development of a new variety of rape plant with high biomass and/or oleic acid contents is required. In order to determine the optimum dose of gamma-ray irradiation, the rape seeds of cvs. Hanra (Hr), Youngsan (Ys), Tammi (Tm), and Tamra (Tr) were irradiated with a 100~4,000 Gy dose range of gamma-rays. Considering the growth factors, the optimum doses were determined to be within the range of 600~1,000 Gy for the selection of useful mutant lines. Six-hundred and eighty-eight (688) $M_2$ mutant lines were obtained from 600~1,000 Gy gamma-ray-irradiated $M_1$ plants through selfing. The growth characteristics, leaf shape, early flowering, and flower color were all investigated. The selected mutant numbers of early flowering, leaf shape, and flower color were 34, 52, and 3 from the four cultivars, respectively. These mutant lines will be used for the development of a new variety of rape plant with high biomass and oleic acid contents.

• Journal of the Korean Society of Radiology
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• v.15 no.3
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• pp.273-279
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• 2021

Metal material inserted into the body have a large difference in density from human tissues or bones around the Metal during CT scans.. Therefore, the Metal material inserted into the body produces Artifact. Metal Artifact, which occurs around Metals, can degrade the quality of CT images, causing confusion when medical team diagnose lesions. Through this experiment, we confirm that the occurrence of Artifacts decrease by using Dual energy CT and MAR algorithm in Single source Dual energy CT. We also want to present basic data on clinical application methods by comparing and analyzing the characteristics of images obtained by each method. Using GE 750HD CT, artificial implants were scanned using general method and Dual energy. Then we apply the MAR algorithm to each image obtained. And all previously acquired images were compared and analyzed the characteristics of the examination, such as image quality evaluation and dose evaluation. Images with MAR algorithm and Dual Energy confirmed a decrease in Metal Artifact. Images with MAR algorithm have reduced Metal Artifact, but have the disadvantage of distorting the details of artificial joint implants. On the other hand images teseted with Dual Energy have the advantage of being able to implement details than those applied with MAR algorithms, it takes longer to reconstruct the image and the exposure dose was about four times higher than those applied with MAR algorithm. In order to locate Metals, such as the post-operative follow-up period, it is useful to apply MAR algorithm to obtain images. And it is more useful to examine with Dual Energy when micro lesion identification, such as cardiac examination, and surgical planning or when tests are performed in diagnostic way.

• Journal of Hydrogen and New Energy
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• v.19 no.2
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• pp.118-123
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• 2008

For the hydrogen recirculation system of the PEMFC (polymer electrolyte membrane fuel cell), the ejector is useful to improve the efficiency of the fuel cell system. However, conventional ejector does not keep its entrainment ratio good when the various power duties is required by the fuel cell system. In this study, the variable multi-ejector acceptable in the whole duty range required from the fuel cell hybrid mini-bus is developed. Consequently, the performance of the developed ejector is verified by the experiments based on the real operating conditions.