• Proceedings of the KIEE Conference
• /
• 1994.07b
• /
• pp.1478-1480
• /
• 1994

In this paper, the microwave absorption properties of two layered absorber were evaluated. The two layer absorber were composed of Ni-Zn ferrite/rubber absorber and Ferroxplana/rubber absorber. The most absorption properties condition were obtained when the transforming layer and absorbing layer were Ferroxplana/robber absorber and Ni -Zn ferrite/rubber absorber. respectivity. The optimal thickness of the transforming and the absorbing layer were 4(mm) and 1(mm), respective1y.

• 한국태양에너지학회:학술대회논문집
• /
• 2011.11a
• /
• pp.93-98
• /
• 2011

A photovoltaic/thermal(PVT)collector produces both thermal energy and electricity simultaneously. The heat from PV modules should be removed for better electrical performance, and can be converted into useful thermal energy. A PVT module is a combination of PV module with a solar thermal collector which forms one device that converts solar radiation into electricity and heat. In general, there are two different types of PVT module: glazed PVT module and unglazed PVT module. On the other hand, two types of the PVT module can be distinguished according to absorber on PV module rear side: the sheet-and-tube absorber PVT module and the fully wetted absorber PVT module. The absorber collector plays an important function in PVT system. It cools down the PV module, while collecting the thermal energy produced in the form of hot water. The aim of this study is to compare the electrical and thermal performance of two different PVT collectors, one with the rectangular tube and the other with fully wetted absorber PVT collectors. For this paper, the PVT collectors with two different types of thermal absorber were made, and both the thermal and electrical performance of them were measured in outdoor, and the results were compared. The experimental results were analyzed that the thermal efficiency of the fully wetted absorber PVT collector is about 8.7% higher than the sheet-and-tube absorber PVT collector, and for the electrical efficiency, the fully wetted absorber PVT collector had about 7% higher than the rectangular tube absorber.

• International Journal of Internet, Broadcasting and Communication
• /
• v.10 no.4
• /
• pp.1-5
• /
• 2018

The property of magnetic field and properties of EMW(Electro Magnetic Wave) absorption with multi-shaped EMW absorber was simulated. As a magnetic field having high density was showed at bottom of EMW absorber, simulation showed that overall EMW was absorbed at the bottom of multi-shaped absorber. The absorption properties of EMW according to thickness of absorber showed that it enhanced about 50-60 percent. Also, EMW absorption properties was checked with surface area of EMW absorber. A cylinder-shaped EMW absorber exhibited good property among multi-shaped EMW absorber based on these result.

• KIEAE Journal
• /
• v.11 no.3
• /
• pp.69-73
• /
• 2011

In general, there are two types of PVT module depending on the existence of the glass in front of PV module: glazed and unglazed. On the other hand, the water-type PVT modules can be classified into two types, according to absorber type: the sheet-and-tube absorber PVT module and the fully wetted absorber PVT module. The aim of this study is to analyze the electrical and thermal performance of a water-type PVT module with fully wetted absorber. For this study, a prototype of unglazed PVT module with fully wetted absorber was designed and built, and both the thermal and electrical performances of the prototype module were measured in outdoor conditions. A conventional mono-crystalline Si PV module was tested alongside the PVT module for their electrical performance comparison. The results showed that the thermal efficiency of the PVT module was average 51% and its electrical efficiency was average 14.3% in mean fluid temperature $10-40^{\circ}C$, whereas the electrical efficiency of the conventional PV module was average 12.6%. It is found that the electrical efficiency of the PVT module was improved by approximately 14% compared to that of the PV module. The temperature of PVT module becomes lower due to the cooling effect by the fluid of the absorber. The results proved that the electrical efficiency was higher when the mean fluid temperature was lower.

• 한국태양에너지학회:학술대회논문집
• /
• 2011.04a
• /
• pp.121-126
• /
• 2011

The heat from PV modules should be removed for better electrical performance, and can be converted into useful thermal energy. A photovoltaic-thermal(PVT) module is a combination of PV module with a solar thermal collector which forms one device that converts solar radiation into electricity and heat simultaneously. In general, there are two different types of PVT module: glazed PVT module and unglazed PVT module. On the other hand, two types of the PVT module can be distinguished according to absorber on PV module rear side: the sheet-and-tube absorber PVT module and the fully wetted absorber PVT module. In this paper, the experimental performance of water type unglazed PVT with fully wetted absorber was analyzed. The electrical and thermal performance of the unglazed PVT were measured in outdoor conditions, and the results were analyzed. The experimental results showed that the thermal efficiency of the PVT module was 42% average, and its electrical efficiencies were 15.2% and 14.2% average, respectively, for the mean fluid temperature of $10-20^{\circ}C$ and $21-30^{\circ}C$. Thermal efficiency depends on solar radiation, mean fluid temperature and ambient temperature. The PVT module temperature is related to the cooling effect of the PV module by the fluid of the absorber. The results proved that the electrical efficiency was higher when the mean fluid temperature was lower.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.65 no.1
• /
• pp.13-17
• /
• 2016

EMC (Electro Magnetic Compatibility) of the electrical railway must be ensured for safety of passenger. Maglev trains has not friction between the wheels and the rails because levitation by an permanent magnets, electromagnets and superconducting magnets etc. So, it is advantageous to maintain a high speed without noise and vibrations. In this paper, we investigated that the magnetic field of the before and after installation electromagnetic waves absorber in order to analyze the effects of electromagnetic waves. The theoretical analysis of the electromagnetic wave absorber was simulated using finite element method. The magnetic field properties of electromagnetic waves absorber were measured by EMI (Electro Magnetic Interference) test receiver.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.16 no.3
• /
• pp.1-6
• /
• 2008

The performance of shock absorber is directly related to the car behavior and performance, both for handling and comfort. Most of compact car are assembled the passive shock absorber for cost effect but some of compact driver want better performance of shock absorber than standard parts. Therefore, they want the semi-active suspension control system instead of standard damper system. But they only can change the mechanical damping control shock absorber at A/S market. The mechanical damping control shack absorber can not vary the damping force in driving condition so they do not satisfy the mechanical damping control shock absorber system. In this study, electrically damping force controlled shock absorber system is developed based on the mechanical damping force control damper system. This system can vary damping force by switch on dashboard in driving condition. And, this system can satisfy the requirement of tuning market. Therefore, it is expected the system to show the engineering capability of korean damper company and to increase export market share to oversea damper market.

• Proceedings of the KSME Conference
• /
• 2003.04a
• /
• pp.881-886
• /
• 2003

Vibration control of plates with a passive electrical damper is presented in this paper. This electrical absorber, piezoelectric patches connected with a resistor and an inductor in series, is analogous to the damped mechanical vibration absorber. For estimating the effectiveness of piezoelectric absorber, the governing equations of motion are derived using a classical laminate plate theory and Hamilton principle. The developed theoretical analyses are validated experimentally for simply-supported aluminum plates in order to demonstrate the performance of passive electrical damper. The result shows that the vibration amplitude is reduced about 14dB for the targeted first vibration mode.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.27 no.10
• /
• pp.1778-1784
• /
• 2003

Vibration control of plates with a passive electrical damper is presented in this paper. This electrical absorber, piezoelectric patches connected with a resistor and an inductor in series, is analogous to the damped mechanical vibration absorber. For estimating the effectiveness of piezoelectric absorber, the governing equations of motion are derived using a classical laminate plate theory and Hamilton principle. The developed theoretical analysis is validated experimentally for a simply-supported aluminum plate in order to demonstrate the performance of passive electrical damper. The result shows that the vibration amplitude is reduced about 14dB for the targeted first vibration mode.

• Proceedings of the KIEE Conference
• /
• 1994.07b
• /
• pp.1406-1408
• /
• 1994

In recently, there is growing demand for microwave absorbing matrial, and for the design method of microwave absorber. We developed a new method to design the matching frequency and matrial thick for ferrite/rubber composite absorber. Ni-Zn ferrite prepared with coprecipitation was compounded with silicon rubber, and, subsequently, pressed to ring specimen. The matrial constant of the ferrite/rubber composite absorber was used to design the matching frequency and matrial thick with matching map. In this study, we could predict matching condition from the design method. Foremore, using matching boundary map, we could also predict the condition of over 20[dB] attenuation.