• KSBB Journal
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• v.29 no.4
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• pp.225-231
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• 2014

A microbial fuel cell (MFC) and bioelectrochemical systems are novel bioprocesses which employ exoelectrogenic biofilm on electrode as a biocatalyst for electricity generation and various useful chemical production. Previous reports show that electrogenic biofilms of MFCs are time varying systems and dynamically interactive with the electrically conductive media (carbon paper as terminal electron acceptor). It has been reported that maximum power point tracking (MPPT) method can automatically control load by algorithm so that increase power generation and columbic efficiency. In this study, we developed logic based control strategy for external load resistance by using $LabVIEW^{TM}$ which increases the power production with using flat-plate MFCs and MPPT circuit board. The flat-plate MFCs inoculated with anaerobic digester sludge were stabilized with fixed external resistance from $1000{\Omega}$ to $100{\Omega}$. Automatic load control with MPPT started load from $52{\Omega}$ during 120 hours of operation. MPPT control strategy increased approximately 2.7 times of power production and power density (1.95 mW and $13.02mW/m^3$) compared to the initial values before application of MPPT (0.72 mW and $4.79mW/m^3$).

• Korean journal of food and cookery science
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• v.24 no.4
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• pp.511-516
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• 2008

In this study, composite flour and dough were prepared with concentrated sweet pumpkin powder(CSPP) at varying concentrations of 3, 6, 9, 12, and 15%. The samples and a control were then compared with regards to quality characteristics, including moisture, protein, and ash contents, farinogram characteristics, amylogram characteristics, and falling number of flour and extensogram characteristics of dough, in an effort to determine the optimal ratio of CSPP in the formulation. As the CSPP content increased, the moisture and protein contents of the flour increased, whereas the ash contents decreased. With regard to the farinogram characteristics of flour, water absorption, development time, and stability decreased with increasing CSPP content, while weakness increased. The control group evidenced a significantly higher beginning temperature of gelatinization as compared to the CSPP samples. The temperature of maximum viscosity, maximum viscosity, and falling number of flour decreased with increasing CSPP content. With regard to the extensogram characteristics of dough, extensibility decreased with increasing testing time and CSPP content, whereas resistance, maximum resistance, and R/E ratio increased. In conclusion, these results show that $6{\sim}9%$ CSPP may prove very useful as a substitute for wheat flour in the production of hardroll bread, and may provide good nutritional and functional properties.

• Journal of Ocean Engineering and Technology
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• v.23 no.4
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• pp.47-51
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• 2009

Thrust is one of the important performance characteristics of an AUV. At the design stage, the resistance of an AUV at its maximum speed is estimated and then the thrust system is designed, including the propeller diameter, propeller rpm, driving system, and required power. However, it is not possible to be certain that the thrust system has been correctly designed until the AUV is launched and its speed is measured. If data from a propeller open-water test is available, the thrust and torque of the propeller at a certain speed can be estimated. In addition, if the motor's torque characteristics are available, the maximum speed saturated by the induced propeller torque can be estimated. In this paper, an easy technique for estimating the maximum speed of an AUV will be shown, even in a case where additional resistance is gained from appendages not considered at the design stage. Furthermore, the thrust performance changes by adjusting the diameter of the propeller can be easily investigated.

• Journal of Electrical Engineering and Technology
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• v.9 no.1
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• pp.231-238
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• 2014

Adaptive Maximum Torque Per Amp (Adaptive MTPA) control for induction motor drives seeks to achieve a desired torque with the minimum possible stator current regardless of operating points. This is favorable in terms of inverter operation and nearly optimal in terms of motor efficiency. However, the Adaptive MTPA control was validated only from the viewpoint of tracking a desired torque and was not shown that the desired torque is achieved with minimum possible stator current. This work experimentally demonstrates that optimal condition for Adaptive Maximum Torque Per Amp Control Strategy is achieved regardless of rotor resistance variation.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.1332-1334
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• 2002

Thermoelectric generation is the direct energy conversion method from heat th electric power. The conversion method is a very useful utilization of waste energy because of its possibility using a thermal energy below $150^{\circ}C$ This research objective is th establish the thermoelectric technology on a optimum system design method and efficiency, and cost effective thermoelectric element in order to extract the maximum electric power from a wasted hot water. This paper is considered in manufacturing a thermoelectric generator and measuring of electric resistance of module a thermoelectric modules. It was found that the electric resistance of thermoelectric modules was defined as a temperature functions. The relationship between electric resistance and temperature characteristics can be a analogized as function of electric current.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.09a
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• pp.588-589
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• 2005

Current expertise in air-water turbulent flows on stepped chutes is limited to laboratory experiments at low to moderate Reynolds numbers on flat horizontal steps. In this study, highly turbulent air-water flows skimming down a large-size stepped chute were systematically investigated with a $22^{\circ}$ slope (Fig. 1). Turbulence manipulation was conducted using vanes or longitudinal ribs to enhance interactions between skimming flows and cavity recirculating regions (Fig. 2). Systematic experiments were performed with seven configurations. The results demonstrated the strong influence of vanes on the air-water flow. An increase in flow resistance was observed consistently with maximum flow resistance achieved with vanes placed in a zigzag pattern.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.04a
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• pp.130-135
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• 1995

We can consider that the study on early evaluation of strength of concrete is useful to raise safety of building and utility of quality control of concrete is useful to raise safety of building and utility of quality control of concrete. In this paper, was proposed to method early to predict strength of concrete with key parameters, such as Water/Cement(W/C) ratio and Sand / Aggregate(S/A) ratio. Through a series of experiment, the obtained results are summarized as follow. $\circled1$ The ratio of resistance was decteased as the increase of W/C ratio. $\circled2$ The maximum value for the ratio of resistance and compressive strength was presented in the case of 40% S/A ratio. $\circled3$ The relationship. of the ratio of resistance and compressive strength on 28days according to the change of W/C and S/A ratio is to be: $F_{28}=-0.00104R^2 + 2.263R - 935.5$ (W/C Ratio) $F_{28} = 0.007R^2 - 10.693R - 4269.1$ (S/A Ratio)

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.4
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• pp.557-562
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• 2009

Recently, researchers are developing a new, clean, renewable and sustainable energy to the industrial areas and the residential areas. Solar cell and fuel cell energy are presented in this paper. The paper shows the P-I and I-V characteristics of fuel cells which are connected in parallel and series. And the voltage drop of internal resistance of the fuel cell decreases with the increasing of the current of the fuel cell. A voltage drop at the internal resistance is increased according to the current, thus the terminal voltage is decreased. The internal resistance is calculated $0.3[\Omega]$ from maximum power transfer condition.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.04a
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• pp.26-29
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• 2001

Sorption/desorption Study was conducted to determine desorption-resistance hydrophobic organic compounds in natural soils with low organic carbon content. Sorption/desorption characteristics of chlorobenzene and phenanthrene for both PPI (Petro Processors, Inc. Superfund site) and BM (Bayou Manchac), soils were investigated. Desorption was biphasic including reversible and desorption-resistant compartments. The biphasic sorption parameters indicated the presence of appreciable size of desorption-resistant phase in these soils. A finite maximum capacity of desorption-resistant fraction (equation omitted) was observed after several desorption steps. The apparent organic carbon based Partition coefficient, K(equation omitted) was 10$^{4.92{\pm}0.27}$ for PPI soil and 10$^{4.92{\pm}0.27}$ for BM soil, respectively. The difference in K(equation omitted) was attributed to different characteristics in soil organic matter. The results suggest that desorption-resistance should be considered in remediation and risk assessments in natural soils and sediments.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.555-558
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• 2005

The purpose of this study is to evaluate the chemical resistance of polymer powder-modified mortars with special accelerator component. Polymer powder-modified mortars with the accelerator are prepared with various polymer-binder ratios, and tested for flexural and compressive strengths and mass change. Chemicals resistance was tested by dealing with $10\%$ HCl and $5\%\;H_2SO_4$ aqueous solution. As a result, the weight reduction ratio of the mortars decreased with increasing polymer-binder ratio. However, in the viewpoint of strength reduction by chemical attacks, the maximum chemical resistance of the mortars was shown at a polymer-binder ratio of $5\%$.