• Journal of the Institute of Electronics Engineers of Korea TE
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• v.39 no.3
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• pp.1-7
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• 2002

This paper presents a new PLL clock generator that can improve a jitter noise characteristics and acquisition process by designing a multi-PFD(Phase Frequency Detector) and an adaptive charge pump circuit. The conventional PLL has not only a jitter noise caused from such a demerit of the wide dead zone and duty cycle, but also a long delay interval that makes a high speed operation unable. An advanced multi-structured PFD circuit using the TSPC(True Single Phase Clocking) circuit is proposed, in which it shows an excellent functionalities in terms of the jitter noises by designing its circuit with the exact dead zone and duty cycle. Our new designed adaptive charge pump in the loop filter of a PLL can improve an acquisition characteristic by adaptively increasing of current. The Hspice simulation is done to evaluate the performance of the proposed circuit. Simulation result shows that our PLL has under 0.01ns in the dead zone, no influence from the duty cycle of input signals and under 50ns in the acquisition time. This circuit will be able to be used in develops of high-performance microprocessors and digital systems.  

• Journal of Internet Computing and Services
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• v.13 no.3
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• pp.23-30
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• 2012

In order to show the gap between theory and practice, this paper first gives some experimental results for theoretical and real neighbor sets on a test-bed sensor network. The results prove that existing management protocols (e.g., duty-cycling, routing or aggregation) based on the theoretical communication radius cannot achieve their original goal, efficiency. In this paper, we present a practical duty-cycling mechanism based on the real neighbor set, allowing for energy-efficiency. It also guarantees to suppress duplicated transmissions of sensing values with similarity within a specific threshold in each zone (i.e., a portion of intended divided network). Simulation results performed with a set of real sensor data show that our mechanism increases the network life time while guaranteeing the transmission of necessary sensing values.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.10
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• pp.4889-4902
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• 2018

It is a challenging issue to improve the energy efficiency of neighbor discovery in WSNs. This paper proposes an optimal discovery model (ODM) for the first time. Based on the model, we investigate the influence of the relative size of two unequal active slots on the energy efficiency. ODM provides the energy optimal value of the length of the larger active slot at a given duty cycle. Other than existing methods, the worst-case latency bound of ODM is only one period. This is a subversive conclusion, because almost all other related methods are based on a wake-up schedule that contains several periods. We theoretically deduce that ODM can reduce worst-case discovery latency by 43.89% compared to Searchlight-Trim when their duty cycles are the same. The simulations verify the advantage of ODM.

• Journal of KIISE:Information Networking
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• v.35 no.2
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• pp.149-157
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• 2008

Since wireless sensor networks consist of nodes with the constrained battery, energy efficient MAC operation is one of the important issues. Low duty cycle operation is critical to conserve energy in wireless sensor network MAC protocol. Some paper proposed a new approach to low power listening, which employs a short preamble to further reduce energy consumption and to reduce latency. But short preamble suffers from unfair channel access problem since there was no consideration for contention between transmission nodes. Preamble counting proposes a solution to each of these problems by employing node selection information. Simulation results show that the preamble counting provides an improved energy efficiency and fairness of packet delivery.

• Journal of Internet Computing and Services
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• v.10 no.2
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• pp.161-169
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• 2009

The development of Wireless Multimedia Sensor Networks(WMSNs) is getting realized in accordance with the increased demands to provide multimedia data transmission service such as CCTV movie, image chapter information, audio information based on wireless sensor network. It is very important to provide the differentiated quality assurance of service. In this paper, we propose a sensor medium access control protocol based on DSMAC, which provides differentiated Quality of Service(QoS) for delay. A proposed protocol is able to reduce the delay without increasing the energy consumption by adaptively changing the duty cycle according to the buffer occupancy. Simulation results show that the new MAC protocol performs better in terms of latency than S-MAC and DSMAC.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.6 no.7
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• pp.17-26
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• 2016

Information spill was occurred several times in the country due to the negligence of the large internet service providers including SK Communications, Auction, KT. In order to judge the Internet Service Provider(ISP)'s liability in individual data spill caused by hacking, the violation of existing legislation or general principle of law's good faith principle has to be examined. However, based on current ISP's good faith principle, there is no objective standard for judging liability. Such uncertain range of protection action duty based on good faith principle generates complaint toward companies, therefore presentation of objective judgement range index on how to determine this range is needed. However due to the legal characteristic of above-mentioned law, it is not possible to fix the range of protection action duty and regulate it on law. In order to resolve this, rather than concerning simply on legal system level, fusion approach method is needed. Thus, this research will discuss the measure for objective standard for predicting ISP's range of protection action duty through fusion view dividing in technical, legal and administrative aspects.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.42 no.3 s.303
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• pp.63-70
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• 2005

The electrodeless lamps using the induction discharge have a long lifetime and a high tolerance for the variable output conditions of a ballast since they don't need the electrodes. This paper proposed two novel dimming algorithms for the Electrodeless lamps and described the resonant inverter adopted the proposed methods. The proposed dimming algorithms are based on the conventional burst dimming method which is normally adopted for LCD back-lights. One of the proposed algorithms is a improved burst dimming method, which controls the illumination by duty ratio of $5\%$ and its control circuit is formed by simple digital logics. The other algorithm is a burst PWM average duty ratio control method, which controls the illumination by duty ratio of $1\%$ and its control circuit is formed by more complex digital logics than the first method. To verify the validity of the proposed dimming methods, a prototype experimental setup for 100W Electrodeless lamps is carried out and its results are presented in this paper.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.2
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• pp.353-359
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• 2006

As for the characteristic of elements for a lot of communication used in light communication systems, it is affected according to structure of directional coupler. We carried out study on a characteristic of the directional coupler which had waveguide structure to have perturbation phenomenon in this paper and ran simulation on the characteristic that we changed structure of directional coupler too, and was got. Confirmation was able to do that it operated with an optical filter, and the directional coupler which added waveguide structure to produce perturbation phenomenon by the results was able to confirm what we adjusted duty ratio of waveguide structure too, and operated with a more excellent optical filter. Through simulation, the case that duty ratio changed than the case that duty ratio of waveguide structure was $50\%$ was able to get an excellent answer characteristic of a -l8dB degree.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.11
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• pp.2627-2635
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• 2013

In this paper micro-scale solar energy harvesting system with a new MPPT control are proposed. In conventional solar energy harvesting systems, continuous perturbation techniques of the clock frequency or duty cycle of a power converter have been used to implement MPPT(Maximum Power Point Tracking) control. In this paper, we propose a new MPPT technique to control the duty cycle of a power switch powering a power converter. The proposed circuit is designed in $0.35{\mu}m$ CMOS process, and the designed chip area including pads is $770{\mu}m{\times}800{\mu}m$.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.5C
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• pp.500-505
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• 2002

In this paper, a novel architecture of programmable divider with fifty percent duty cycle output and programmable dividing number has been proposed. Through HSPICE simulation, a 900MHz frequency synthesizer with proposed frequency divider has designed in a standard 0.25$\mu\textrm{m}$ CMOS technology. To verify the operation of proposed frequency divider, a chip had been fabricated using 0.65$\mu\textrm{m}$ 2-poly, 3-metal standard CMOS processing and experimental result shows that the proposed frequency divider works well. The designed voltage controlled oscillator(VCO) has a center frequency of 900MHz, a tuning range of ${\pm}$10%, and a gain of 154MHz/V. The simulated frequency synthesizer performance has a settling time of 1.5${\mu}\textrm{s}$, a frequency range from 820MHz to 1GHz and power consumption of 70mW at 2.5V power supply voltage.