• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.3
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• pp.179-184
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• 1999

In the past ten years, $LiMn_2O_4$-based spinels have been extensively studied as positive electrode materials for lithium-ion batteries. To improve the cycle performance of spinel $LiMn_2O_4$ as the cathode of 4V class lithium secondary batteries, spinel phases $LiMn_2O_4$ were prepared at various temperatures ranging form 600-900$^{\cire}C$ in air. The results showed that charge.dischare capacity of $LiMn_2O_4$ varied at 1st temperature from $200^{\circ}C to 600^{\circ}C$ increase with increasing temperature. $LiMn_2O_4$ synthesized at 2nd temperature $750^{\circ}C$excellent charge.discharge capacity, efficiency and cyclability compared to the samplesynthesized different temperatures. The value of lst charge.discharge capacity was 121mAh/g, 118mAh/g, Also, the efficiency value was about 97%.

• Journal of the Korean Solar Energy Society
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• v.34 no.5
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• pp.53-63
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• 2014

Caltech's Linde-Robinson Laboratory was originally built in 1932 featuring a Spanish mission-style design, whose function was to facilitate a solar observatory with a coelostat solar telescope dome and a solar shaft extending from the roof to more than 36.58m below the ground. The building has now been transformed into a cutting-edge center for research and instruction in global environmental science that retains its original character while setting new standards in energy efficiency and green design. It is the first LEED Platinum lab in the USA for renovation of a historical research building, consuming only one-sixth of the energy that the lab's comparable laboratories do. This work introduces various energy and environmental strategies hired for its sustainable rehabilitation and, especially, examines the functional validity of solar telescope daylighting by a coelostat. Observations were made on the llumination of underground floors, where illuminances of 40~50 lx were measured.

• Korean Journal of Computational Design and Engineering
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• v.20 no.1
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• pp.11-21
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• 2015

Currently, the United States, the United Kingdom, Australia etc. are actively utilizing energy simulation for efficiency evaluation of building energy. However, domestic energy efficiency assessment system doesn't use energy simulation system properly at present: parameters based architecture plans and Ashrae Standard are inputted for the evaluation, because the input parameters for the simulation haven't been established yet. This fact causes poor reliability during energy simulation, as the values of the two standards are different from each other. Therefore, the aim of the study is to set domestic standard parameter for BIM-based energy performance evaluation, focusing on possession area per person of occupants at government office in Korea. We found that the difference among the result values occurred approximately 3% in the energy simulation. As a result of the analysis, possession area per person of occupants in Government office is $31.87m^2$. Other input parameters may be set based on this. This will increase the reliability of energy simulation through a domestic standard parameter.

• Nuclear Engineering and Technology
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• v.46 no.6
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• pp.737-752
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• 2014

As condition-based maintenance (CBM) has risen as a new trend, there has been an active movement to apply information technology for effective implementation of CBM in power plants. This motivation is widespread in operations and maintenance, including monitoring, diagnosis, prognosis, and decision-making on asset management. Thermal efficiency analysis in nuclear power plants (NPPs) is a longstanding concern being updated with new methodologies in an advanced IT environment. It is also a prominent way to differentiate competitiveness in terms of operations and maintenance costs. Although thermal performance tests implemented using industrial codes and standards can provide officially trustworthy results, they are essentially resource-consuming and maybe even a hind-sighted technique rather than a foresighted one, considering their periodicity. Therefore, if more accurate performance monitoring can be achieved using advanced data analysis techniques, we can expect more optimized operations and maintenance. This paper proposes a framework and describes associated methodologies for in-situ thermal performance analysis, which differs from conventional performance monitoring. The methodologies are effective for monitoring, diagnosis, and prognosis in pursuit of CBM. Our enabling techniques cover the intelligent removal of random and systematic errors, deviation detection between a best condition and a currently measured condition, degradation diagnosis using a structured knowledge base, and prognosis for decision-making about maintenance tasks. We also discuss how our new methods can be incorporated with existing performance tests. We provide guidance and directions for developers and end-users interested in in-situ thermal performance management, particularly in NPPs with large steam turbines.

• Journal of Korean Society of Water and Wastewater
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• v.24 no.5
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• pp.537-548
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• 2010

Recently the Government has announced updated water quality standards for wastewater treatment effluent (become effective in 2012). That includes highly enforced regulations for T-P, BOD and COD, and a large budget, in particular for phosphorus removal, was set by the Ministry of environment. Chemical coagulation destabilizes colloidal particles so that particles grow to larger flocs, and solid particles are removed by solid-liquid separation. The efficiency of chemical coagulation depends on a various factors, including coagulant types and costs, construction and operation costs for the treatment facilities and so on. The proper selection should be based on the treatment efficiency of coagulants and underlying costs. The current research was to evaluate the treatment efficiencies of coagulants on a variety of wastewater influents and to develop saturation curves for several water quality parameters. Typical $Al_2(SO_4)_3$ and $FeCl_3$ were tested under a range of coagulant concentrations. The pollutant removal efficiencies of chemical treatment both for the $Al_2(SO_4)_3$ and $FeCl_3$ were especially high for T-P, followed by SS, BOD and COD. Correlation test also proved the highest relationship between SS and T-P.

• Journal of Environmental Science International
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• v.14 no.7
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• pp.683-689
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• 2005

The consecutive combination process of a biological process as the pre-treatment and a chemical process as the post-treatment is applied for the dyeing wastewater. The poor efficiency of biological treatment using pure oxygen makes the chemical treatment cost high. It is necessary to improve the efficiency of biological treatment in order to reduce the cost of chemical treatment. The purpose of this paper is to find the minimum dose of chemical reagent to fit the Discharged Water Quality Standards for the different biological treatment effluents. Results revealed that the minimum dosage of Fenton's reagent lead to save the cost of chemical treatment based on the guideline dose in the treatment plant. The possible maximum saving reagents was up to $70\%$ for the effluent of the pilot plant packed with the carrier imbedded microorganisms which were selected from the present treatment plant.

• Journal of Information Technology Applications and Management
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• v.9 no.2
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• pp.17-32
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• 2002

Even though the distance education via web has a great advantage to overcome time and space, its problem is that the management of trainees is not efficient compared with classroom and group education. This problem is a great obstacle to the objects and achievement standards of distance education, giving controversial arguments to the advocators of distance education. Distance educators need to monitor the trainees'participation and responses continuously and offer appropriate feedback to the trainees. However, the existing distance education system only focuses on teaching and learning activities, and as a result, the efficient management function of distance education is not available. Accordingly, the study attempts to find out the appropriate managing elements of distance teacher training in order to effectively achieve the goals of teacher training and the efficient management of distance education. Also, it proposes distance teacher training management system that offers appropriate feedback to trainees, applying the derived elements of distance teacher training to the training processes. To verify the efficiency of the system, hypotheses on related items of distance teacher education and learning types are suggested, and the achievement degree of learning and its relations are investigated through questionnaire of learning types. In addition, a system using UML which is the standard of object-oriented modeling language is devised, so. that mutual management, language independence and convenient development environment as well as reusability can be offered, and so the design standardization and efficient system realization could be achieved, while flexible change of system according to education process and computing environment is possible.

• Journal of the Optical Society of Korea
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• v.17 no.5
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• pp.376-383
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• 2013

The design of the LEDs lighting in general household illumination was proposed and compared with the fluorescent lighting in this study. Using the LED as a light source would promote energy saving lighting for household illumination purposes. We used the LightTools and DIALux software to design and simulate different standards of illuminance, different correlated color temperatures and different color rendering indices for household environments. The power consumption and efficiency of traditional illuminated light sources and an LED light source with the same standard of illuminance for lighting the household environment were analyzed and compared with each other. Finally, our results show the advantages of using white-light LEDs for lighting and household illumination.

• ETRI Journal
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• v.36 no.4
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• pp.528-536
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• 2014

High Efficiency Video Coding (HEVC) is the most recent video coding standard to achieve a higher coding performance than the previous H.264/AVC. In order to accomplish this improved coding performance, HEVC adopted several advanced coding tools; however, these cause heavy computational complexity. Similar to previous video coding standards, motion estimation (ME) of HEVC requires the most computational complexity; this is because ME is conducted for three inter prediction modes - namely, uniprediction in list 0, uniprediction in list 1, and biprediction. In this paper, we propose an efficient inter prediction mode (EIPM) decision method to reduce the complexity of ME. The proposed EIPM method computes the priority of all inter prediction modes and performs ME only on a selected inter prediction mode. Experimental results show that the proposed method reduces computational complexity arising from ME by up to 51.76% and achieves near similar coding performance compared to HEVC test model version 10.1.

• Particle and aerosol research
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• v.13 no.2
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• pp.53-63
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• 2017

As semiconductor process was highly integrated, particle contamination became a major issue. Because particle contamination is related with process yields directly, particles with a diameter larger than half pitch of gate should be controlled. PBMS (Particle beam mass spectrometry) is one of powerful nano particle measurement device. It can measure 5~500 nm particles at ~ 100 mtorr condition in real time by in-situ method. However its usage is restricted to research filed only, due to its big device volume and high price. Therefore aperture changeable aerodynamic lenses (ACALs) which can control particle focusing characteristics by changing its aperture diameter was proposed in this study. Unlike conventional aerodynamic lenses which changes particle focusing efficiency when operating condition is changed, ACALs can maintain particle focusing efficiency. Therefore, it can be used for a multi-monitoring system that connects one PBMS and several process chambers, which greatly improves the commercialization possibility of the PBMS. ACALs was designed based on Stokes number and evaluated by numerical method. Numerical analysis results showed aperture diameter changeable aerodynamic lenses can focus 5 to 100 nm standard particles at 0.1 to 10 torr upstream pressure.