• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.95-98
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• 2006

Data collected by sensors in field are transmitted to the base station gathering all of data. Because sensors have to gather data in surroundings and periodically transmit data to the base station, it makes energy consumed much. In this paper, we propose the scheme that is to avoid traffic congestion with achievement of energy efficiency, so collected data is transmitted efficiently. This is to adjust transmission rate differently in case of increasing or decreasing traffic and minimize the energy consumption with setting ideal options up basic CSMA(Carrier Sense Multiple Access) protocol in each sensor. Through the simulation, we find the ideal CSMA options and apply the proposed scheme of traffic control mechanism to them, then show energy efficiency and effective traffic control mechanism.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.8
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• pp.1947-1954
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• 2009

Camera-captured car plate images contain much variation and noise and the character images in a plate are typically very small. We attempted to improve the plate identification efficiency suitable for this undesirable condition. We experimented various image preprocessing and feature extracting methods and the very effective features that can compensate one feature's limitation is determined through extensive experiments. Finally two very effective features that can complement the limitations of each other feature(classifier) are determined and the efficiency is proved by recognition experiments. This approach is very necessary when handling plate character images which are typically small, various, and noisy. Individual classification result, confidence factor, region name relation and feedback verification are comprehensively considered to enhance the overall recognition efficiency. The efficiency of our method is verified by a recognition experiment using real car plate images taken from traffic roads.

• Journal of Power Electronics
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• v.3 no.4
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• pp.249-258
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• 2003

This paper presents a high-efficient and cost effective three-phase AC/DC-DC/AC power conversion system with a single two-switch type active Auxiliary Resonant DC Link (ARDCL) snubber circuit, which can minimize the total power dissipation. The active ARDCL snubber circuit is proposed in this paper and its unique features are described. Its operation principle in steady-state is discussed for the three phase AC/DC-DC/AC converter, which is composed of PWM rectifier as power factor correction (PFC) converter, sinewave PWM inverter. In the presented power converter system not only three-phase AC/DC PWM rectifier but also three-phase DC/AC inverter can achieve the stable ZVS commutation for all the power semiconductor devices. It is proved that the proposed three-phase AC/DC-DC/AC converter system is more effective and acceptable than the previous from the cost viewpoint and high efficient consideration. In addition, the proposed two-switch type active auxiliary ARDCL snubber circuit can reduce the peak value of the resonant inductor injection current in order to maximize total system actual efficiency by using the improved DSP based control scheme. Moreover the proposed active auxiliary two-switch ARDCL snubber circuit has the merit so that there is no need to use any sensing devices to detect the voltage and current in the ARDCL sunbber circuit for realizing soft-switching operation. This three-phase AC/DC-DC/AC converter system developed for UPS can achieve the 1.8% higher efficiency and 20dB lower conduction noise than those of the conventional three-phase hard-switching PWM AC/DC-DC/AC converter system. It is proved that actual efficiency of the proposed three-phase AC/DC-DC/AC converter system operating under a condition of soft switching is 88.7% under 10kw output power.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3B
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• pp.321-327
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• 2006

This study was performed to provide basic information for evaluating the efficiency and applicable extent of photocatalysis for the treatment of swine wastewater. Acid area was more efficient than neutral and alkalic areas in wastewater treatment, and level of pH3 was the most effective and the treatment efficiency continually increased as the amount of photocatalyst was increased. When the photocatalyst was increased, $TCOD_{Mn}$ was removed faster than chromaticity. Pollutants were more effectively eliminated with both UV light illumination and $TiO_2$ than with either UV or $TiO_2$ alone. The removal efficiency was increased with the addition of $H_2O_2$ as an oxidant, but the removal efficiency was decreased with over an dosage of $H_2O_2$. The optimal dosage of $H_2O_2$ was 200 mg/L. Continuous injection of $H_2O_2$ was required for effective oxidation.

• Journal of Korean Society for Quality Management
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• v.28 no.3
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• pp.133-144
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• 2000

Many organizations have developed their own information systems not only for internal efficiency but also for effectiveness of external customer services. One of the most effective service tools for their customers is the use of information technology. The web technology is rapidly becoming one of the most effective tools for online customer services. In order to gain competitive edge, organizations must have effective web site planning methods for their customer service. A study on traditional information systems planning methodologies has been conducted and they are compared with web site planning techniques. Cases of web sites in order to Improve customer relationship are analyzed. finally, a new conceptual framework for web site planning strategy for e-CRM is proposed in this paper. In order to support effective web site planning, online customer contact points and online service activities are defined and classified as several stages. And, web site strategies corresponding to each customer service activities are developed and proposed, With this framework, organizations can build competitive web strategies for improving their online customer relationships, thereby increasing customer satisfaction.

• Proceedings of the KIEE Conference
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• 1987.07b
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• pp.1556-1559
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• 1987

In this paper, a new state assignment method is proposed for the implementation of the area-effective control part. Introducing the, concept of adjacency matrix to control table generated by SDL(Symbolic Description Language) hardware compiler, a state assignment method is proposed with which minimal number of flip flops and effective number of product terms can be obtained to accomplish the area-effective implementation. Also, with substituting the assigned code to state transition table, boolean equations are obtained through 2-level logic minimization. Proposed algorithm is programmed in C-language on VAX-750/UNIX and b efficiency is shown by the practical example.

• Nuclear Engineering and Technology
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• v.34 no.1
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• pp.22-29
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• 2002

The angular correlation effect was investigated for Co-60 ${\gamma}$-ray spectroscopy by using HPGe detector and the effective angular correlation was theoretically calculated by considering the finite detector solid angle. For the calculation of effective angular correlation, the detection efficiency as a function of ${\gamma}$-ray incident direction was obtained by using Monte Carlo method and the first interaction model. The results and the methods used in the calculation are discussed.

• Journal of Fisheries and Marine Sciences Education
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• v.25 no.3
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• pp.705-715
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• 2013

This Paper presented the reduction methods of $CO_2$ emission from ships during voyage. In order to decrease $CO_2$ emission during voyage the equation was established and conducted the study about the relationship between ship speed, the propulsive efficiency and its $CO_2$ production. The results obtained from the examinations are as follows : 1. $CO_2$ emission from sailing ships can be decreased by reducing specific fuel oil consumption of main diesel engine, coefficient of total resistance and ship speed and also by increasing propeller efficiency. 2. Diesel-electric propulsion system is more effective than diesel-mechanical system to decrease the level of $CO_2$ emission during long voyage. 3. Good condition of ship's hull surface, rudder and propeller's surface can decrease the quantity of fuel oil and $CO_2$ emission by reducing the resistance of ship that can rise the propeller efficiency 4. $CO_2$ emitted from ships can be decreased in a global scale by giving attention to the synthetic transport efficiency.

• Journal of Information Technology Applications and Management
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• v.27 no.1
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• pp.1-13
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• 2020

This study aims to measure the efficiency and productivity change of 30 domestic construction companies from 2010 to 2018 using data envelopment analysis(DEA) and Malmquist productivity index (MI). In particular, we used the number of employees, capital stock, and non-current assets as input variables, and sales and net income as ouput variables for the analysis. The dataset used for the analysis of efficiency and productivity changes is the employee profile and financial statements for the companies from 2010 to 2018. We found that the MI of the 30 companies is greater than one since 2013. This is because many years of TEC (Technical Efficiency Change) is greater than 1, which means that the productivity index increases as the TEC increases. In addition, the MI value was less than 1, which lowered the productivity of construction firms in 2018. The results of the study may help decision makers to find effective future management plans by analyzing the internal and external factors.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.11 no.3
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• pp.13-19
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• 2015

This study was aimed at the heating tank with a screw-rotation device for improving the thermal efficiency of electric boiler. In the proposed system, analysis items were the heater rod surface temperature variation, reaching time for set temperature and thermal efficiency. The following conclusions are obtained from this experimental study. (1) When screw speed increases, the time reaching for set temperature tended to be shorter. (2) When the rotation speed becomes 300 rpm, the surface temperature difference between the right and left heater rod decreases by 49%, from $19.7^{\circ}C$ to $9.7^{\circ}C$ in average. (3) When the rotation speed is over 250 rpm, proposed heating tank structure appeared to be effective in terms of thermal efficiency. Thermal efficiency with the rotation speed 300 rpm is improved by 3.8% compared to the case of rotation speed 0 rpm.