• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.2
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• pp.71-77
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• 2009

A novel phase-locked loop(PLL) architecture with multiple charge pumps for fast locking has been proposed. The proposed PLL has three charge pumps. The effective capacitance and resistance of the loop filter can be scaled up/down according to the locking status by controlling the direction and magnitude of each charge pump current. The fast locking PLL that changes its loop bandwidth through controlling charge pumps depending on locking status has been designed. The capacitor usually occupying the larger portion of the chip is also minimized with the proposed scheme. Therefore, the PLL size of $990{\mu}m\;{\times}\;670{\mu}m$ including resistors and capacitors at the bandwidth of 29.9KHz has been achieved. It has been fabricated with 3.3V $0.35{\mu}m$ CMOS process. The locking time is less than $6{\mu}s$ with the measured phase noise of -90.45dBc/Hz @1MHz at 851.2MHz output frequency.

• Current Industrial and Technological Trends in Aerospace
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• v.7 no.2
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• pp.76-84
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• 2009

In this review an attempt is made to give the background to the current trends in foreign developments in the ceramic matrix composites for space vehicles. The lightweight and high temperature specific modulus properties of ceramic composites have continued to develop for designing advanced propulsion structures and for increasing space vehicle performances. Those applications require advanced materials with good resistance to high temperatures, to oxidation environments and to mechanical stresses. The advantages of ceramic matrix composites are the low specific weight, the high specific strength over a wide temperature ranges, and their good damage tolerance compared to tungsten, pyrographites and polycrystalline graphites. Due to these advantages ceramic matrix composites are currently used in rocket engine chamber, nozzle, solar array, radar antenna, mirror support structures, hypersonic leading edge articles, heat shields, reentry vehicle nose tips, and radiators for spacecraft. Various processes are discussed together with examples of current application so that some of the advanced technologies can be possibly applied to Korean space technology.

• Weed & Turfgrass Science
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• v.2 no.3
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• pp.221-229
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• 2013

This paper reviews current status of weed control practices in herbicide-resistant crops to examine weed management strategies in cope with cropping herbicide-resistant crops in the near future. Herbicide-resistant crops were rapidly adopted weed management technologies due to broad-spectrum weed control without crop injury. Transgenic glyphosate-resistant cultivars in soybean, corn, canola, and cotton were adopted to manage weeds at lower cost in a simplified weed management system. Dual stack crops with glyphosate and glufosinate resistance were developed to control glyphosate resistant weeds in corn, soybean and cotton. New multiple herbicide-resistant crops with resistance to glyphosate and glufosinate, acetolactate synthase (ALS) inhibitors, synthetic auxin herbicides, 4-hydroxyphenyl pyruvate dioxygenase (HPPD) inhibitors or acetyl Coenzyme A carboxylase (ACCase) inhibitors will expended the utility of existing herbicide technologies to manage the evolution of resistant weeds. However, herbicide resistant crops alone cannot solve weed problems and thus studies on diverse weed managements using an array of alternating herbicides of mode of action, mechanical, and cultural practices are needed for integrated weed management systems in the future.

• The Korean journal of helicobacter and upper gastrointestinal research
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• v.18 no.3
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• pp.150-156
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• 2018

Precision medicine stands for 4Ps - precise, preventive, participatory, and personal; in which "precision" is important because the current modern medicine starts from "trial and error," and "one does not fit all". Current targeted therapies for cancer have changed treatment approaches and led the precision medicine; however, clinical use of liquid biopsy, using blood or other liquid specimens to characterize circulating tumor cells (CTC) or tumor genes instead of biopsies of tumor tissues, still awaits availability of more information regarding non-invasive cancer detection and characterization, prediction of treatment response, monitoring the disease course and relapse possibilities, identification of mechanisms of drug resistance, and newer pathogenesis. In this review, we will introduce the basic concept of CTC, circulating cell free DNA, and exosomes and their possible application for gastric cancer relevant with Helicobacter pylori infection.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.3
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• pp.175-180
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• 2015

With progress in industrialization, facilities for generating, delivering, and receiving high levels of electric power are in great demand. The scale of electric power equipment is increasing in both size and complexity. This has contributed to the development of our modern, high-tech and information-based society. However, if the generation of electric power is suspended due to unexpected accidents at power facilities or power stations, a range of equipment the operations of which are dependent on electric power can be damaged, causing substantial socioeconomic losses in an industrial society. A great deal of time and money would be expended to repair damaged facilities at a power station, causing enormous economic loss.In order to detect the deterioration processes of power cables, and to prevent the destruction of power cables, the operation status of power cables should be monitored on a regular basis. We have installed equipment at Korea Western Power Co., Ltd., located in Taean, in order to predict and prevent the destruction of power cables. This is an entirely new installation: a set of equipment invented specifically to measure the insulation resistance of power cables. Installation of the equipment does not cause the flow of earth fault current. This ensures accurate measurement of insulation resistance values by the equipment. We have been studying this equipment in order to develop preventive technology that would show the deterioration processes of power cables.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2001.11a
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• pp.7-7
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• 2001

The increasing interest in light weight materials coupled to the need for cost -effective processing have combined to create a significant opportunity for aluminum P/M. particularly in the automotive industry in order to reduce fuel emissions and improve fuel economy at affordable prices. Additional potential markets for Al PIM parts include hand tools. Where moving parts against gravity represents a challenge; and office machinery, where reciprocating forces are important. Aluminum PIM adds light weight, high compressibility. low sintering temperatures. easy machinability and good corrosion resistance to all advantages of conventional iron bm;ed P/rv1. Current commercial alloys are pre-mixed of either the AI-Si-Mg or AL-Cu-Mg-Si type and contain 1.5% ethylene bis-stearamide as an internal lubricant. The powder is compacted in closed dies at pressure of 200-500Mpa and sintered in nitrogen at temperatures between $580~630^{\circ}C$ in continuous muffle furnace. For some applications no further processing is required. although most applications require one or more secondary operations such as sizing and finishing. These sccondary operations improve the dimension. properties or appearance of the finished part. Aluminum is often considered difficult to sinter because of the presence of a stable surface oxide film. Removal of the oxide in iron and copper based is usually achieved through the use of reducing atmospheres. such as hydrogen or dissociated ammonia. In aluminum. this occurs in the solid st,lte through the partial reduction of the aluminum by magncsium to form spinel. This exposcs the underlying metal and facilitates sintering. It has recently been shown that < 0.2% Mg is all that is required. It is noteworthy that most aluminum pre-mixes contain at least 0.5% Mg. The sintering of aluminum alloys can be further enhanced by selective microalloying. Just 100ppm pf tin chnnges the liquid phase sintering kinetics of the 2xxx alloys to produce a tensile strength of 375Mpa. an increilse of nearly 20% over the unmodified alloy. The ductility is unnffected. A similar but different effect occurs by the addition of 100 ppm of Pb to 7xxx alloys. The lend changes the wetting characteristics of the sintering liquid which serves to increase the tensile strength to 440 Mpa. a 40% increase over unmodified aIloys. Current research is predominantly aimed at the development of metal matrix composites. which have a high specific modulus. good wear resistance and a tailorable coefficient of thermal expnnsion. By controlling particle clustering and by engineering the ceramic/matrix interface in order to enhance sintering. very attractive properties can be achicved in the ns-sintered state. I\t an ils-sintered density ilpproaching 99%. these new experimental alloys hnve a modulus of 130 Gpa and an ultimate tensile strength of 212 Mpa in the T4 temper. In contest. unreinforcecl aluminum has a modulus of just 70 Gpa.

• Journal of Korea Port Economic Association
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• v.18 no.2
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• pp.65-90
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• 2002

Despite the importance and necessity, the 3PL has not been activated to date. Among many views, customers claim that logistics service provider(LSP) are not prepared or capable of offering satisfactory 3PL services, while LSP emphasize the lack of mutual trust, closed corporate culture of the customer and excessive demand for reducing the costs. With this keeping in mind, it surveyed difference of perception between users and providers of 3PL services in terms of the actual status of using 3PL services, the degree of satisfaction and key factors for selecting 3PL provider through the questionnaire. As shown in this study, 43.3％ of the respondents outsourced logistics services. However, Most company outsourced only inland transportation (49.5％) which is a simple and limited scope of 3PL services, but it also indicated that the percentage of users have ranged was less then 10% in outsourcing their whole logistics sector to 3PL provider and employing other logistics functions. Among respondents, a majority of the service provider stated that they offered satisfactory cost-saving to the customers, while users felt that the degree of satisfaction for using 3PL services was evaluated as at an average level and they more highly regarded the strong partnership of their 3PL provider rather than the saving of cost and improvement of customer's services. Moreover, in contrast to the 3PL providers which regard the most important factor for selecting 3PL service provider is the logistics cost quoted, users of 3PL services felt that the quality of services was more significant than the reduction of cost, and this tendency for selecting 3PL providers was shown in more advanced countries. While users of 3PL services indicated that the main reason for not using 3PL services was to avoid disclosing information of their business and it costs much for employing 3PL providers than doing themselves, 3PL providers thought it was due to reluctancy of opening information and resistance from the logistics division engaged in logistics activities concerned. Accordingly, providers and users of 3PL services should trust each other and prepare plan to activate 3PL services under the collaborative relationships as soon as possible.

• Journal of Plant Biotechnology
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• v.3 no.2
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• pp.67-81
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• 2001

Traditionally, genetic variability is generated by an extensive crossing program, which is complemented by strict selection to identify useful new recombinants. Plant biotechnology offers many opportunities for breeders to solve certain breeding problems at the molecular level. The tissue culture methodology and the genetic modification of economically important monocotyledons have undergone a revolution in the last decade. As the production of transgenic plants is a complex procedure, including the uptake of DNA molecules into the cells, the integration of foreign nucleotide sequences into the host genomic DNA and the expression of new genes in a controlled way, and as there are still many unsolved questions, further development is necessary. The methodology opens up the possibility of introducing novel genes that may induce resistance to diseases and abiotic stresses, allow the modification of dough quality and the dietetic quality of proteins, and increase the levels of micronutrients such as iron, zinc, and vitamins. In the present review, the authors would like to summarise the most important advances in wheat transformation.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.64 no.1
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• pp.29-34
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• 2015

DC bus electrolytic capacitors are used in variety of equipments as smoothing element of the power converters because it has high capacitance for its size and low price. It is responsible for frequent breakdowns of many static converters and inverter drive systems. Therefore it is important to diagnosis monitoring the condition of an electrolytic capacitor in real-time to predict the failure of power converter. In this paper, the on-line remote diagnosis monitoring system for DC BUS electrolytic capacitors of power converter using low-cost type Zigbee communication modules is developed. To estimate the health status of the capacitor, the equivalent series resistor(ESR) of the component has to be determined. The capacitor ESR is estimated by using RMS computation using AC coupling method of DC link ripple voltage/current. The Zigbee communication-based experimental results show that the proposed remote DC capacitor diagnosis monitoring system can be applied to DC/DC converter and UPS successfully.

• Smart Structures and Systems
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• v.1 no.4
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• pp.355-368
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• 2005

Large and complex structures are being built now-a-days and, they are required to be functional even under extreme loading and environmental conditions. In order to meet the safety and maintenance demands, there is a need to build sensors integrated structural system, which can sense and provide necessary information about the structural response to complex loading and environment. Sophisticated tools have been developed for the design and construction of civil engineering structures. However, very little has been accomplished in the area of monitoring and rehabilitation. The employment of appropriate sensor is therefore crucial, and efforts must be directed towards non-destructive testing techniques that remain functional throughout the life of the structure. Fiber optic sensors are emerging as a superior non-destructive tool for evaluating the health of civil engineering structures. Flexibility, small in size and corrosion resistance of optical fibers allow them to be directly embedded in concrete structures. The inherent advantages of fiber optic sensors over conventional sensors include high resolution, ability to work in difficult environment, immunity from electromagnetic interference, large band width of signal, low noise and high sensitivity. This paper brings out the potential and current status of technology of fiber optic sensors for civil engineering applications. The importance of employing fiber optic sensors for health monitoring of civil engineering structures has been highlighted. Details of laboratory studies carried out on fiber optic strain sensors to assess their suitability for civil engineering applications are also covered.