• 한국태양에너지학회:학술대회논문집
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• 2008.11a
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• pp.184-189
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• 2008

The excess heat that is generated from PV modules can be removed and converted into useful thermal energy. A photovoltaic/thermal(PVT) module is a combination of photovoltaic module with a solar thermal collector, forming one device that converts solar radiation into electricity and heat simultaneously In general, two types of PVT can be distinguished: glass-covered PVT module, which produces high-temperature heat but has a slightly lower electrical yield, and uncovered PVT module, which produces relatively low-temperature heat but has a somewhat higher electrical performance. In this paper, the experimental performance of water type unglazed PVT combined module, analyzed. The electrical and thermal performance of the module were measured in outdoor conditions, and the results are analyzed. The results showed that the thermal efficiency of the PVT module was 27.05% average and its PV efficiency was about 11.85% average, both depending on solar radiation, inlet water temperature and ambient temperature.

• Journal of Korean Society on Water Environment
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• v.21 no.5
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• pp.496-499
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• 2005

Power Plant is requested, by environmental bodies and fisherman, to correct the pollution of coastal area due to the outflow of foam from the outlet of the power plants. Foam wastewater cause a lot of environmental problems, expecially in aesthetic points of view. Therefore, It is needed to be collect from the stream into nearby ocean, and the collected foams should be treated before being discharged into nearby ocean. The most effective and feasible treatment method researched for the effective treatment of foam wastewater generated at the power plants. The result of the test is confirmed with collecting Foam wastewater by inhalation force. The treatment pilot ($3m^3/hr$) collected wastewater was operated by Biological degradation method(Aerobic/anaerobic Processes) for approximately two months. It was removed SS, COD, nutrient(T-P, T-N), etc. The System is expected successfully by Minimizing the operating costs such as electricity, repair expenses, chemicals and supplies expenses.

• Journal of the Optical Society of Korea
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• v.15 no.4
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• pp.362-367
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• 2011

Organic ($Alq_3$) film, which was coated on a donor plate, was transferred to an organic light emitting diode (OLED) substrate with help of heat generated by a dithering laser beam. The laser beam was diffracted in an acousto-optic modulator (AOM), then focused on the laser-to-heat converting layer of the donor plate; the focused spot followed trajectories guided by rotation of a Galvano-mirror. Three different functional waveforms, sine wave, square wave, and saw tooth wave were applied to the AOM as modulation signal to generate the dithering beam. The fluorescence microscope images of the donor plate showed that the patterns of removed $Alq_3$ film were affected considerably by the modulation waveforms and the phase difference between adjacent dithering beams. Further, the printed images of Alq3 film on the OLED substrate were different from the patterns of removed Alq3 film. Atomic force microscope images indicated that not only direct transfer but also deposition by sublimated vapor of Alq3 contributed to the pattern formation. Printed patterns affected considerably the electricity-to-light conversion characteristics of OLEDs. For uniform transfer, not only the phase relation of dithering beam lines but also adequate waveform were important.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.11
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• pp.865-869
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• 2011

A cantilever-type piezoelectric generator has advantages of simple structure, ease of fabrication and large displacement by transverse vibration of a beam. It is easy to control the natural frequency, and also possible to increase the output power by changing the length, width, and thickness of the generator. In particular, the length increases, the natural frequency sharply decreases, and vice versa. Hence, the natural frequency can widely be controlled by using change in the length of elastic body. In this paper, the generator was designed and fabricated to change natural frequency using the slides of the case. In addition, the generating characteristics were confirmed through finite element analyses and vibration experiment. As a result, the maximum output characteristics could be generated due to resonance phenomenon although any frequency of external force was applied.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.792-797
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• 2009

The excess heat that is generated from PV modules can be removed and converted into useful thermal energy. A photovoltaic-thermal(PVT) module is a combination of photovoltaic module with a solar thermal collector, forming one device that receives solar radiation and produces electricity and heat simultaneously. In general, two types of PVT can be classified: glass-covered PVT module, which produces high-temperature heat but has a slightly lower electrical yield, and uncovered PVT module, which produces relatively lower temperature heat but has a somewhat higher electrical performance. In this paper, the experimental performance of two types of the PVT combined module(water type), glazed(glass-covered) and unglazed, was analyzed. The electrical and thermal performance of the PVT combined modules were measured in outdoor conditions, and the results were compared.

• Journal of the Korean Society of Clothing and Textiles
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• v.20 no.1
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• pp.19-27
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• 1996

The purpose of this study is the investigation of the physical properties, handle variation of polyester fabrics grafted methacrylic acid. The results are as follow 1. In the case of moisture recovery, MA-g-PET results in an improvement of approximately 4% when the graft ratio reaches 25%, whilst Na-MA-g-PET results in an improvement of approximately 9% when the graft ratio reaches 20%. 2. The static electricity of Na-MA-g-PET, is rarely generated when the graft ratio exceeds 10% . 3. The T.H.V. indicate that the values had deteriorated in the case of MA-g-PET, whilst the N a-Ma-a.PET values demonstrated superiority. 4. The value resulting from the MA-g-PET and Na-MA-g-PET treatment methods are calculated as being 0.0130, whilst the value pursuant to graft ratio is 0.0000.

• Journal of Microbiology and Biotechnology
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• v.11 no.5
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• pp.863-869
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• 2001

A systematic study of microbial fuel cells comprised of alkalophilic Bacillus sp. B-31 has been carried out under various operating conditions. A significant amount of electricity was generated when redox mediators were used. Among the phenothiazine-type redox dyes tested, azure A was found to be the most effective both in maintaining a high cell voltage and for the long-term operation. The maximum efficiency was and for the long-term operation. The maximum efficiency was obtained at ca. $50^{\circ}C$ giving an open circuit voltage of 0.7V. A small change in temperature did not significantly affect the cell performance, but a rapid decrease in performance was observed below $20^{\circ}C$ and above $70^{\circ}C$. It was noticeable that fuel cell efficiency and discharge pattern depended strongly on the carbon source used in the initial culture medium. Regardless of the initial carbon sources, only glucose and trehalose were utilized as substrates. Galactose, however, was not substantially utilized except when galactose was used in the initial medium. Glucose, in particular, showed $87\%$ coulombic efficiency, which was the highest value ever reported, when Bacillus sp. was cultured in a maltose-containing medium. This study demonstrates that highly efficient microbial fuel cells can be constructed with alkalophilic microorganisms by fine-tuning the operating conditions and by carefully selecting carbon sources in the initial culture medium.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.594-599
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• 2009

Recent developments such as concern over global warming, depletion of fossil fuels and increase in energy demands by the increasing world population has eventually lead to mass production of electricity using renewable sources. Apart from wind and solar, ocean holds tremendous amount of untapped energy in forms such as geothermal vents, tides and waves. The current study looks at generating power using waves and the focus is on the primary energy conversion (first stage conversion) of incoming waves for different models. Observation of flow characteristics and the velocity in the augmentation channel as well as the front guide nozzle are presented in the paper. A numerical wave tank was used to simulate the waves and after obtaining the desired wave properties; the augmentation channel plus the front guide nozzle and rear chamber were integrated to the numerical wave tank. The waves in the numerical wave tank were generated by a piston type wave maker which was located at the wave tank inlet. The inlet which was modeled as a plate wall moved sinusoidally with the general function, x=asin$\omega$t The augmentation channel consisted of a front nozzle, rear nozzle and an internal fluid region representing the turbine housing. The analysis was performed using the commercial CFD code ANSYS-CFX.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.55 no.8
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• pp.378-385
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• 2006

In this study, a method measuring signal propagation direction in human body was developed by using passive electrical properties of the body. The measured method of the signal propagation direction is to apply basic characteristic of electricity to the human body; when a voltage is set to a conducted medium, according to the polarity of the conducted voltage, the voltage rising or drop is generated. And using this concept, it is able to estimate the direction of electrical signal on the human body. The passive electrical properties were measured and the direction of signal propagation was estimated on the followings; between the flexor carpi radialis, between arms, between legs, between an arm and a leg, between the cervical vertebra and the upper limb, between the sacral vertebra and the leg, between the cervical vertebra and the tendon of triceps brachii, and between the sacral vertebra and the calcaneal tendon. As the result of experiments, the passive electrical properties were increased from l[Hz] to 50[kHz] of the inputted frequencies and showed at saturating tendency after that. And also, the estimated signal propagation directions using the developed method in this study agreed with the expected directions exactly at each part of the human body.

• Ceramist
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• v.22 no.1
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• pp.56-69
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• 2019

Recent advances in low-power sensors and transmitters are driving the search for standalone power sources that utilize unused ambient energy. These energy harvesters can alleviate the issues related to the installation and maintenance of sensors. Particularly piezoelectric energy harvesters, with the ability to convert ambient mechanical energy into useful electricity, have received significant attention due to their high energy density, low cost and operational stability over wide temperature and pressure conditions. In order to maximize the generated electrical power, the natural frequency of the piezoelectric energy harvester should be matched with the dominant frequency of ambient vibrations. However, piezoelectric energy harvesters typically exhibit a narrow bandwidth, thus, it becomes difficult to operate near resonance under broadband ambient vibration conditions. Therefore, the resonating of energy harvesters is critical to generate maximum output power under ambient vibration conditions. For this, energy harvesters should have broadband natural frequency or actively tunable natural frequency with ambient vibrations. Here, we review the most plausible broadband energy harvesting techniques of the multi-resonance, nonlinearity, and self-resonance tuning. The operation mechanisms and recent representative studies of each technique are introduced and the advantages and disadvantages of each method are discussed. In addition, we look into the future research direction for the broadband energy harvester.