• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.107-110
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• 2009

The photovoltaic power system is effected by atmospheric condition. Therefore, The maximum power point tracking(MPPT) algorithm of the Photovoltaic (PV) power system is needed for high efficiency. Many MPPT techniques have been considered in past, but In this paper, the author analyzes widely known P&O MPPT algorithm and ImP&O algorithm, and presents new MPPT algorithm complementing weaknesses of other two algorithms.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1386-1387
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• 2011

Maximum power point tracking(MPPT) techniques are used in photovoltaic systems to maximize the PV array output power by tracking continuously the maximum power point which depends on panels temperature and on irradiance conditions. In this paper, the controller of the stand-alone PV system applicable to various fields are designed. The improved P&O MPPT and traditional P&O MPPT method was applied. This improved algorithm consists of a constant perturbation with an step control which will make easier the controller PV power data acquisition process. This strategy of control has, in first time, been validated by PSIM simulations. After, been field test. The experimental results show that the improved P&O method increased the PV output power compare to traditional P&O method.

• Korean Journal of Materials Research
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• v.19 no.11
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• pp.613-618
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• 2009

We designed new compositions for lead free and low temperature sealing glass frit of $ZnO-V_2O_5-P_2O_5$ system, which can be used for PDP (Plasma Display Panel) or other electronic devices. The $ZnO-V_2O_5-P_2O_5$ system can be used as a sealing material at temperatures even lower than 430$^{\circ}C$. This system, however, showed lower bonding strength with glass substrate compared to commercialized Pb based sealing materials. So, we added $TiO_2$ as a promoter for bonding strength. We examined the effect of $TiO_2$ addition on sealing behaviors of $ZnO-V_2O_5-P_2O_5$ glasses with the data for flow button, wetting angle, temporary & permanent residual stress of glass substrate, EPMA analysis of interface between sealing materials and glass substrate, and bonding strength. As a result, sealing characteristics of $ZnO-V_2O_5-P_2O_5$ system glasses were improved with $TiO_2$ addition, but showed a maximum value at 5 mol% $TiO_2$ addition. The reason for improved bonding characteristics was considered to be the chemical interaction between glass substrate and sealing glass, and structural densification of sealing glass itself.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.1
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• pp.75-79
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• 2012

Maximum power point tracking(MPPT) techniques are used in photovoltaic systems to maximize the PV array output power by tracking continuously the maximum power point which depends on panels temperature and on irradiance conditions. This paper proposes a variable step size MPPT algorithm which can improve the MPPT speed and accuracy. Depending on insolation and temperature, the MPPT controller gives optimized step size. The effectiveness of the proposed system is verified thorough PSIM simulation and experiments on a 50[W] prototype. The experimental results confirm that the PV power of the improved P&O method is higher than that of the traditional P&O method.

• Journal of The Korean Society of Grassland and Forage Science
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• v.11 no.1
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• pp.60-67
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• 1991

This experiment was conducted to investigate the effects of starch addition on the fermentative quality and dry matter digestibility(DMD) of Kudzu(Puerari~ thzmbergii Bentham) silage. The herbages was ensiled by the conventional methods in small plastic silo of 7.5 liters with addition of starch of 0 %, 2 %, 4 74, 6 % and 8 %, respectivery. The samples of kudzu silage were separated into leaf and stem, and was determined the pH, organic acid and characteristics of fiber such as neutral detergent fiber(NDF), acid detergent liber(ADF) and acid detergent lignin(ADL). The DMD of leaf and stem silage were evaluated by pepsin-cellulase technique method. The energy values(tota1 digestible nutrients, TDN; digestible energy, DE; metaboliz;~bie energy. ME) were calculated by DMD. The results obtained were as follows: 1. The fiberous meterials(such as NDF, AIIF and ADL) of leaf and stem were decreased with increasing levels of starch(p

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.10
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• pp.907-911
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• 2006

In this paper, we propose a new structure that improves the on-state voltage drop and switching speed in Insulated Gate Bipolar Transistors(IGBTs), which can be widely used in high voltage semiconductors. The proposed structure is unique in that the collector area is divided by $SiO_2$, whereas the conventional IGBT has a planar P+ collector structure. The process and device simulation results show remarkably improved on-state and switching characteristics. Also, the current and electric field distribution indicate that the segmented collector structure has increased electric field near the $SiO_2$ corner, which leads to an increase of electron current. This results in a decrease of on-state resistance and voltage drop to $30%{\sim}40%$. Also, since the area of the P+ region is decreased compared to existing structures, the hole injection decreases and leads to an increase of switching speed to 30 %. In spite of some complexity in process procedures, this structure can be manufactured with remarkably improved characteristics.

• Journal of Industrial and Engineering Chemistry
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• v.67
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• pp.199-209
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• 2018

Polyethersulfone (PES)/sulfonated $TiO_2$ ($STiO_2$) nanoparticles (NPs) UF blended membranes were fabricated with different loadings of $STiO_2$. The modified membranes exhibited significant improvement in surface roughness, porosity, and pore size when compared to the PES membrane. The $P-STiO_2$ 1 and $P-TiO_2$ 1 blended membranes exhibited higher water flux, approximately 102.4% and 62.6%, respectively, compared to PES. SPP-$STiO_2$ and $P-STiO_2$ showed lower Rir fouling resistance than the $P-TiO_2$ blended membrane. Overall, the $STiO_2$-blended membranes provide high hydrophilicity permeability, anti-fouling performance, and improved BSA rejection attributed to the hydrogen bonding force and more electrostatic repulsion properties of $STiO_2$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.277-277
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• 2010

We present facile chemical route stabilizing dispersion of carboxylated single-Walled carbon nanotubes (SWCNTs) in ZnOsol prepared by using diethanolamine as a stabilizer. The dispersion was stabilized via capping of carboxyl groups on the SWCNT surface by a titania layer. We also demonstrated that the conductivity of the films prepared P3/$TiO_2$/ZnO as enhanced by therml treatment, and the thermal stbility of the film improved hybridization with ZnO sol pristine P3, P3/$SiO_2$ and P3/$TiO_2$ hybrid films.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.03b
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• pp.41-41
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• 2010

We present facile chemical route stabilizing dispersion of carboxylated single-walled carbon nanotubes (SWCNTs) in ZnOsol prepared by using diethanolamine as a stabilizer. The dispersion was stabilized via capping of carboxyl groups on the SWCNT surface by a titania layer. We also demonstrated that the conductivity of the films prepared P3/$TiO_2$/ZnO as enhanced by therml treatment, and thethermal stbility of the film improved hybridization with ZnO sol pristine P3, P3/$SiO_2$ and P3/$TiO_2$ hybrid films.

• Journal of the Korean Ceramic Society
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• v.16 no.1
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• pp.26-30
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• 1979

The microstructures and memory core characteristics of substituted lithium ferrites with addition of $Bi_2O_3$, $V_2O_5$, $Nb_2O_3$, and $P_2O_5$ were investigated. The effects of composite flux on the sintering of the substituted lithium ferrites were also studied. The results show that the addition of $Bi_2O_3$, $V_2O_5$, and $Nb_2O_5$ enhances sintering whereas $Sb_2O_3$ and $P_2O_5$ inhibits it, and that the addition of $Nb_2O_5$ results in uniform grain size while the addition of $Bi_2O_3$ or $V_2O_5$ results in non-uniformity in grain size. When $P_2O_5$ was added with $V_2O_5$ or $Bi_2O_3$, however, it results in uniform grain size and improved memory core properties.