• Journal of Korea Multimedia Society
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• v.16 no.7
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• pp.862-869
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• 2013

In order to support a cell-independent traffic asymmetry, the conventional TDD system cannot avoid crossed time slot (CTS) interference. Moreover, the TDD/FDD hierarchical overlay cellular systems is taken into account as a generally accepted cell model in a heterogeneous radio environment. In this paper, we propose an interference resolving radio resource allocation technique in a TDD-OFDMA cellular system that overlays a FDD-CDMA cell. In our proposed scheme, we exploit under-used FDD-CDMA uplink resource by TDD mobile abiding by a region based time slot(TS) allocation which in turn mitigates CTS interference considerably. It is demonstrated that combined with under-used resource utilization scheme based on mobile's location, the proposed technique can reduce CTS interference considerably and support the asymmetric traffic in TDD system.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.269-274
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• 1998

This paper describes a scaled model for PWM thyristor current-source inverter with a commutation circuit. The system consists of a 6-pulse thyristor bridge and an LC resonant circuit with thyristor switches, which offers thyristors to have turn-off capability for PWM operation with minimal switching losses. The proposed system can be used as a reactive power compensator with PWM operation for the utilitity application. There would be two advantages in the proposed system over the existing voltage source inverter. One is the low system cost due to using the conventional thyristors. Another is easy expansion of system operation voltage because th series operation of thyristor devices is already proven in HVDC system.

• Journal of Electrical Engineering and Technology
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• v.5 no.3
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• pp.423-430
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• 2010

Particle swarm optimization (PSO) algorithm is designed to find a single global optimal point. However, the PSO needs to be modified in order to find multiple optimal points of a multimodal function. These modifications usually divide a swarm of particles into multiple subswarms; in turn, these subswarms try to find their own optimal point, resulting in multiple optimal points. In this work, we present a new PSO algorithm, called coupling PSO to find multiple optimal points of a multimodal function based on coupling particles. In the coupling PSO, each main particle may generate a new particle to form a couple, after which the couple searches its own optimal point using non-stop-moving PSO algorithm. We tested the suggested algorithm and other ones, such as clustering PSO and niche PSO, over three analytic functions. The coupling PSO algorithm was also applied to solve a significant benchmark problem, the TEAM workshop problem 22.

• The KSFM Journal of Fluid Machinery
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• v.11 no.1
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• pp.46-51
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• 2008

A stability analysis has been made for a newly designed gate of intake tower of reservoir. The analysis is composed of finding the natural frequency of the gate and the frequency induced by water flowing over and through the gate. ANSYS is employed to calculate the natural frequency of the gate and SC/Tetra is utilized for calculating flow field around the gate, which in turn gives the frequency of pressure force fluctuation on the gate. In addition to the safety analysis, the present study presents how the gate selectively intakes a muddy water layer located in the middle depth of reservoir.

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 2002.10a
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• pp.125-134
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• 2002

Crop Protection Products (CPPs) are a useful weapon in our fight against the pests, diseases and weeds that harm or destroy our food. To be effective CPPs need to exhibit some persistence. The consequence of this is that residues of the original material or its metabolites may remain on food and thus there is a potential for the intake of such residues. The issue of CPP residues in food is an emotional subject and is rarely debated rationally or supported by scientific facts. Media headlines like “Poison in our food” or “These days enough Pesticides (CPPs) are sprayed onto vegetables to turn you into one” are testimony to the high level of emotion that surrounds the subject of CPP residues in food. Recent surveys of consumers have indicated that more than 80 percent view CPP residues in food as a “serious hazard”. This significantly exceeds concerns over drugs, hormones in meat, nitrates in food, irradiated foods, food additives, or artificial colours.

• Korean Journal of Poultry Science
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• v.15 no.4
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• pp.277-280
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• 1988

As a whole, the improvement of the weight gain ratio has rather a clear effect for the groups fed live yeast especially at 0.1% level, comparing with the control, and the nutrient digestibility is also improved, noticeably in protein digestibility. Feed intake is not, however, increased for the live yeast fed groups comparing with the control. The live yeast supplements are apparently responsible for the overall improvement in the nutrient availability and this, in turn, resulted in the weight gain of treated groups over the control.

• International Journal of Precision Engineering and Manufacturing
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• v.8 no.3
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• pp.24-44
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• 2007

Cylindrical grinding is one of the important metal cutting processes used extensively in the finishing operation of discrete components. The inherent high cutting temperature in grinding if not controlled may lead to rapid tool wear, which in turn will lead to dimensional inaccuracy. The very nature of the grinding mechanism in material removal impairs the grounded surfaces by inducing residual stress, micro cracks and other thermal damages at the machined surface. This paper is an attempt to review some of the surface integrity issues in cylindrical grinding taken up and reported by number of researchers over the years. This review may have been planned to be useful to the researchers and other professionals interested to work on grinding.

• Korean Journal of Organic Agriculture
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• v.17 no.4
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• pp.463-481
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• 2009

Regional Agricultural Cluster(RAC) at Asan area has been formed with Purundeul farming union corporation(Purundeul) as the center from the year 2005. Originally, RAC has been proceeded by Ministry for Food, Agriculture, Forestry and Fisheries (MFAFF) all over the nation from 2005. This RAC has helped Asan area to establish the foundation of environmentally friendly agriculture(EFA) searching for nutritional cycle. This also made jumping age turn developing age in EFA at Asan area. The number of Purundeul producer members was 386 farmers in 2008. Purundeul introduced organic livestock farming(Korean beef cattle; Hanwoo) for proceeding EFA searching for nutritional cycle in 2007, and had 719 cattle at the end of March 2009. Feedstuff materials for organic livestock is mostly produced from seeding farming by-products within Asan or the country. Asan RAC had built factories for feedstuff producing and beef processing with producers' investment.

• Biotechnology and Bioprocess Engineering:BBE
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• v.7 no.2
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• pp.112-116
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• 2002

Effects of artificial electron donors to deliver reducing power on enzymic denitrification were investigated using nitrate reductase and nitrite reductase obtained from Ochrobactrum antroyi. The activity of nitrite reductase in the soluble portion was almost the same as that in the precipitated portion of the cell extract. Nitrate removal efficiency was higher with benzyl viologen than with methyl viologen or NADH as an artificial electron donor. The turn-over numbers of nitrate and nitrite reductase were 14.1 and 1.9 umol of nitrogen reduced/min$.$mg cell extracts, respectively when benzyl viologen was used as an electron donor.

• 한국정보디스플레이학회:학술대회논문집
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• 2000.01a
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• pp.49-50
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• 2000

5.2" microtip field emission displays (FEDs) with high voltage applications are fabricated. Nano-structural analysis on microtips is performed for the reliable operation of FEDs. Chemical compositions on the apex of microtips are fully analyzed. A charging mechanism on spacers is simulated and experimentally confirmed with micro-images. A gas-aging mechanism is also studied with integration step of FEDs. The brightness of more than 300 $cd/m^2$ is achieved. In addition, as a new concept, 9" color carbon nanotube FEDs (CNT-FEDs) are introduced using well-aligned carbon nanotubes on glass substrates by paste squeeze and surface treatment techniques. A number of carbon nanotubes, $5-10/{\mu}m2$, are uniformly distributed over a large area. The turn-on fields of 1 $V/{\mu}m$ and field emission currents of 1.5 mA at 3 $V/{\mu}m$ are acquired. Different mechanisms between microtip FEDs and CNT-FEDs are discussed.