• 한국정보디스플레이학회:학술대회논문집
• /
• 2008.10a
• /
• pp.57-60
• /
• 2008

Over 5lm/W white luminous efficacy was obtained by 11" color test panel with narrowed discharge electrodes combined with high Xe partial pressure. By using optical spectroscopic methods, it was suggested that the electron heating efficiency is the most significant to improve the plasma efficiency in our experimental conditions.

• Proceedings of the KSR Conference
• /
• 2010.06a
• /
• pp.470-474
• /
• 2010

Up until now, power centralized trains have been produced due to the maintenance convenience and comfortableness, but there are some problems, such as limitation of viscosity and maintenance difficulty of railroad due to recently increasing axle mass. In order to improve the problems, power decentralized trains have been developed to improve traction power. In the case of using electrical braking system, it is possible to improve braking friction power. Induction motors have been developed for power decentralized high speed train because of less structural defection, and low maintenance and production cost. However, induction motors have limitations, such as assuring enough power capacity and efficiency with reduced size. PMSM (Permanent magnet synchronous motor) have been newly developed to improve shortcomings of induction motors. The PMSM can be produced small and light weighted. Also if the PMSM and induction motors have the same size and power capacity, the PMSM have better power efficiency. In this pater, the prototype and modified type of PMSM for "High-speed Electric Multiple Unit-400km/h eXperimmen" will be introduced.

• Journal of Korea Society of Digital Industry and Information Management
• /
• v.14 no.3
• /
• pp.115-125
• /
• 2018

In order to examine the ways to improve the efficiency of R&D investment, this paper presents analysis on both quantitative and qualitative efficiency of R&D projects. As Korea's R&D investment has significantly increased in recent years, the efficiency of R&D investment has attracted attention. In this paper, a Data Envelopment Analysis(DEA) method is used to construct models for quantitative efficiency and qualitative efficiency analysis. Based on a cases of agricultural R&D projects of Korea, the efficiency of national R&D projects were analyzed and their quantitative and qualitative efficiencies are compared. As a result, statistically significant difference between quantitative and qualitative efficiency was found. Also, characteristics of Decision Making Units(DMUs) which can influence both quantitative and qualitative efficiency were identified. In particular, the stage of a R&D project has significant impact on R&D efficiency. This study suggests that in order to enhance R&D efficiency both quantitative and qualitative nature of outputs should be considered when measuring R&D efficiency.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.9
• /
• pp.9-16
• /
• 2020

Wireless charging has been considered an essential part of recent mobile devices. Moreover, various wireless charging systems have emerged through many studies. Among the systems, in the 2D flat coil system, the transmitter coil and receiver coil are arranged horizontally as close as possible to improve the charging efficiency. Nowadays, the 3D coil system has been proposed by adding some slope to flat 2D coils to reduce the volume. On the other hand, the 3D coil system has a lower charging efficiency than the 2D system that decreases rapidly with increasing distance. This paper proposes a new system that improves the low efficiency and charging freedom, which are the drawbacks of the existing 3D systems. The proposed system was designed in three-dimensions, and another transmitter coil was added to the transmitter coil to improve the transmission efficiency and flexibility. The measurement showed that the charging efficiency of the proposed system was 40.10% when the distance between coils was 8 mm, which is 20.5 % improvement over the existing one. The proposed method can be applied when new wireless charging systems are designed and improve charging efficiency can be improved.

• Proceedings of the KSR Conference
• /
• 2007.11a
• /
• pp.974-981
• /
• 2007

Seoul Metro has operated the air cooling equipment established in a machine room of a station building to improve our services focused on our customers who use Seoul Metro during the summer season. However, a new set of problems has arisen with the cooling tower to support a heat exchange of cooling water. One of them is loss of efficiency in the air conditioner. The leading cause of this problem is that we use an underground type of the cooling tower. As the machine room of a station building is located in the underground of inner city because of the nature of the subway, it is difficult to establish the cooling tower on the ground. The underground structure of the No. $1{\sim}4$ subway line is unsuitable for the location requirements of the underground type of the one because it has a limited space to set up the air cooling equipment, for example, the cooling tower and a ventilating opening. As a result of such an unfavorable condition, the cooling tower doesn't work efficiently and the warmth of cooling water because of insufficiency of a heat exchange and a refrigerator's technical obstacle such as a high-temperature and a high-pressure has arisen. Accordingly, the efficiency of the air conditioning is getting lower and lower. Another problem is too wasteful with water. Each station uses the water over 30 tons every day with waterworks to replenish the cooling tower such as a evaporation, a scattering and a distribution of water. Nevertheless, the more an air conditioner increase, the more the use of water supply increase. For this reason, we can't help wasting an enormous amount of water and discharging the congelation of a low temperature(about $15^{\circ}C$) occurred in a heat exchanger inside an air conditioner. The purpose of this study is to analyze the utility of congealing water to improve efficiency of the air cooling equipment and save energy as a supplementary water for the cooling tower.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.19 no.2
• /
• pp.26-34
• /
• 2011

Hybrid powertrain systems have been developed to improve the fuel efficiency of internal combustion engines. In the case of a parallel hybrid powertrain system, an engine and a motor are directly coupled. Because of the hardware configuration of the parallel hybrid system, friction and the pumping losses of internal combustion engines always exists. Such losses are the primary factors that result in the deterioration of fuel efficiency in the parallel-type hybrid powertrain system. In particular, the engine operates as a power consumption device during the fuel-cut condition. In order to improve the fuel efficiency for the parallel-type hybrid system, cylinder deactivation (CDA) technology was developed. Cylinder deactivation technology can improve fuel efficiency by reducing pumping losses during the fuel-cut driving condition. In a CDA engine, there are two operating modes: a CDA mode and an SI mode according to the vehicle operating condition. However, during the mode change from CDA to SI, a serious fluctuation of the air-fuel ratio can occur without adequate control. In this study, an air-fuel ratio control algorithm during the mode transition from CDA to SI was proposed. The control algorithm was developed based on the mean value CDA engine model. Finally, the performance of the control algorithm was validated by various engine experiments.

• Journal of the Institute of Electronics Engineers of Korea CI
• /
• v.41 no.4
• /
• pp.1-8
• /
• 2004

When the PCI 2.2 bus master requests data using Memory Read command, the target device my hold PCI bus without data transfer for a long time because the target device requires time to prefetch data internally. Because the PCI bus usage efficiency and the data transfer efficiency are decreased due to this situation, the PCI specification recommends to use the Delayed Transaction mechanism to improve the performance. But the mechanism doesn't fully improve performance because the target device doesn't blow prefetch data size exactly. In this paper, we propose a new method to transfer data efficiently when the bus master reads data from the target device. The bus master informs the target device the exact read data size using prefetch request using Memory Write command. The simulation result shows that the proposed method has the higher data transfer efficiency than the Delayed Transaction about 10%.

• Journal of the Korea Furniture Society
• /
• v.23 no.1
• /
• pp.26-37
• /
• 2012

This is the study about the New Formation Developement, the Changeable Table Design with Units that made of Wasted Wood to use restricted material rationally and to improve the space efficiency in the Table Design. We made some changeable table design with units that made of laminated wood wasted. And we found out the following formative characteristic and physical merits through this study. First, the space efficiency can be improve technically through the unit combination and organic transfomation of the specific form and a new method by laminated wood make the personal originality and the structral stability be built up. Second, there are some merits, moveable convenience and variable layout by the combination or transformation or personal fondness so that economical efficiency and variable of design can be improved. Third, we can remove original faults inside wood like a knot or not-uniform of wood organ when we laminate wood so that we use proper units that have original beauty of wood and can represent mild mood of furniture wholly. Fourth, much more strengthen tensile strength by the reciprocal action among the units that be made of laminated wood reduces wood's metamorphosis like bending or twisting so that the uniformity of wood can be gain and furniture's metamorphosis can be reduced. According to changes of nature environment, the difficulty of supply and demand for wood may be happen. According to changes of life style these days, supply and demand for environment friendly material, processing technique and developement of design to improve the efficiency of using space must be very important factor in morden furniture design. So we propose changeable furniture design by using new environment friendly meterial and processing method from this study.

• Journal of Digital Convergence
• /
• v.17 no.12
• /
• pp.181-190
• /
• 2019

The purpose of this study is to evaluate the operational efficiency of Chinese e-commerce companies and to present measures to improve efficiency. This paper selected 16 enterprises as the research objects, from the e-commerce demonstration enterprises of the Ministry of Commerce of China in 2017-2018, to conduct an empirical study on the operating efficiency of e-commerce enterprises. By using DEA method, we selected 3 input and 2 output indicators to measure the input-output efficiency of enterprises from input-oriented. Using different model in DEA, we calculated the technical efficiency, pure technical efficiency and scale efficiency, also efficiency based on the sample of 2018 and horizontal analysis from 2016 to 2018. The analysis showed that the overall efficiency of Chinese e-commerce companies was continuously improving, and that their business capabilities and business scale were also gradually improving. Through the calculation of efficiency, we evaluated the competitiveness of the e-commerce demonstration enterprises, and explored measures to improve their management efficiency. At the same time, it put forward some reasonable suggestions to adjust the scale, and enhance the competitive advantage.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.62 no.11
• /
• pp.1544-1549
• /
• 2013

Recently, the linear compressors with the free piston driven by the linear motor have widely attention in the cooling apparatus such as a refrigerator due to high efficiency. The method of using triacs as a linear motor drive is not satisfactory to improve the efficiency of the linear compressor. In this paper, the performance of the linear compressor using a PWM inverter such as the efficiency is investigated with the variations of both mechanical resonant frequency and electrical resonant frequency. The control loop for controlling both the piston stroke and efficiency is suggested. Through simulation and experimental studies, the performance of both the stroke and angle controls for improving the efficiency of the linear compressor is verified.