• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 학술대회 논문집 정보 및 제어부문
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• pp.448-450
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• 2005

A ubiquitous network allows all users to access and exchange information of any kind freely at any time, from anywhere, and from any appliance through the use of broadband and mobile access. Bluetooth commincation can provide the missing wireless extension to the heterogeneous network, allowing a more ubiquitous access. In this point of view, the BT specifications define ways for which each BT device can set up multiple connections with neighboring devices to communicate in a multi-hop fashion. this paper provides insights on the Bluetooth technology and on some limitations of the scatternet formations. so that, we describe a new multi-hop routing protocol for the establishment of scatternets. this protocol defines rules for forming a multi-hop topology in two phases. the first phase, topology discovery, concerns the discovery of the node's depth from a root node initiating inquiry process. the second phase forms scatternet topology based on the result of topology discovery.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.533-534
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• 2008

This paper presents a multi-phase ring VCO for low-cost, low-power GPS receiver. In the RF band used in GPS, L1 band is now in commercial-use and L2,L5 are predicting to be commercial-use soon. Thus Wide band PLL and Cost-effective IC solutions are required for future multi-band GPS receiver that received three types band at once. A new PLL architecture for multi-band GPS application is proposed. Ring VCO is even smaller than LC-VCO and a good alternative for low-cost solution. Proposed multi-phase ring VCO offers wide frequency range covering L1, L2, and L5 band, 20% reduction of area, 23% reduction of PLL power and can generate I/Q without extra I/Q generator.

• JSTS:Journal of Semiconductor Technology and Science
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• 제15권6호
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• pp.594-600
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• 2015

A 1.25 GHz multi-phase phase-rotating PLL is proposed for oversampling CDR applications and implemented with a low power and small area. Eight equidistant clock phases are simultaneously adjusted by the phase interpolator inside the PLL. The phase interpolator uses only two complementary clocks from a VCO, but it can cover the whole range of phase from $0^{\circ}$ to $360^{\circ}$ with the help of a PFD timing controller. The output clock phases are digitally adjusted with the resolution of 25 ps and both INL and DNL are less than 0.44 LSB. The proposed PLL was implemented using a 110 nm CMOS technology. It consumes 3.36 mW from 1.2 V supply and occupies $0.047mm^2$. The $jitter_{rms}$ and $jitter_{pk-pk}$ of the output clock are 1.91 ps and 18 ps, respectively.

• 대한임베디드공학회논문지
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• 제8권2호
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• pp.95-102
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• 2013

In this paper, we have studied the performance of the AOA (Angle of Arrival) in multi-antenna systems for LBS (Location Based Services) and we also analyzed the performance of the AOA in SISO (Single Input Single Output) in multipath environments and their differences. The adequacy of AOA positioning in new communication environments was determined. Currently used positioning methods in 3G communication environment has been developed based on SISO. However, the accuracy of SISO-based TOA (Time of Arrival), TDOA (Time Difference of Arrival), AOA positioning techniques degraded in multipath environments. The communication system will be changed and developed. According to enhanced positioning techniques are required. Using antenna characteristics and the phase difference between antennas of LTE-Advanced standard's key technique MIMO system AOA positioning, and SISO based AOA positioning performance were analyzed. We found that AOA technique potential for use based on Multiple antenna systems by computer simulations.

• 전력전자학회논문지
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• 제19권5호
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• pp.415-421
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• 2014

This study proposes a model-based predictive control for interleaved multi-phase DC/DC converters. The power values necessary to adjust the output voltage in the succeeding are predicted using a converter model. The output power is controlled by selecting the optimal duty cycle. The proposed method does not require controller loops and modulators for converter switching. This method can control the converter by calculating the optimal duty cycle, which minimizes the error between the reference and actual output voltage. The effectiveness of the proposed method is verified through simulations and experiments.

• Journal of Advanced Marine Engineering and Technology
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• 제34권7호
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• pp.981-990
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• 2010

The main objective of this study is to investigate the fluid flow and the heat transfer characteristics of nanofluids using multi-phase thermal LBM and to realize theenhancement of heat transfer characteristics considered in the Brownian motion. In multi-phase, fluid component($H_2O$) is driven by Boussinesq approximation, and nanoparticles component by the external force gravity and buoyancy. The effect of Brownian motion as a random movement is modified to the internal velocity of nanoparticles(Cu). Simultaneously, the particles of both the phases assume the local equilibrium temperature after each collision. It has been observed that when simulating $H_2O$-Cu nanoparticles, the heat transfer is the highest, at the particle volume fraction 0.5% of the particle diameter 10 nm. The average Nusselt number is increased approximately by 33% at the particle volume fraction 0.5% of the particle diameter 10 nm when compared with pure water.

• Nuclear Engineering and Technology
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• 제44권8호
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• pp.831-846
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• 2012

KAERI has developed a two-phase CFD code, CUPID, for a refined calculation of transient two-phase flows related to nuclear reactor thermal hydraulics, and its numerical models have been verified in previous studies. In this paper, the CUPID code is validated against experiments on the downcomer boiling and moderator flow in a Calandria vessel. Physical models relevant to the validation are discussed. Thereafter, multi-scale thermal hydraulic analyses using the CUPID code are introduced. At first, a component-scale calculation for the passive condensate cooling tank (PCCT) of the PASCAL experiment is linked to the CFD-scale calculation for local boiling heat transfer outside the heat exchanger tube. Next, the Rossendorf coolant mixing (ROCOM) test is analyzed by using the CUPID code, which is implicitly coupled with a system-scale code, MARS.

• Journal of the Optical Society of Korea
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• 제14권4호
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• pp.351-356
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• 2010

We investigated the combined effect of fiber chromatic dispersion and self-phase modulation (SPM) in multi-channel subcarrier multiplexed (SCM) optical transmission systems. We theoretically analyzed the transmission characteristics of the SCM signals with the effect of SPM and chromatic dispersion in a single-mode optical fiber by numerical simulations based on the nonlinear Schrodinger equation. The numerical simulation results revealed that the effect of fiber dispersion and SPM could occur independently between subcarrier channels in two-channel SCM systems for small optical modulation index (OMI) and large channel spacing. However, for large OMI, small channel spacing, and large fiber launching power, we found a performance degradation of the two-channel system compared to that of a single-channel system. These parameters are therefore important for the optimization of multi-channel SCM systems applicable to radio over fiber networks.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2011년 춘계학술대회논문집
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• pp.259-260
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• 2011

Using modern techniques from scientific computing and numerical analysis, natural phenomena or scientific experiment can be simulated effectively with a computer and used for computer graphics, for example as special effects for the film industry, manufacturing the thin film, multi-phase simulation and image processing. The Level Set method can make those things happen without a lot of difficulties. This method was devised by Osher and Sethian(1988) to represent dynamically moving interfaces as the zero level set of a scalar function that evolves in time. Since then, many researchers have worked on many applications using a Level Set Method. I will give a talk about the applications of the Level Set Method.

• Steel and Composite Structures
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• 제35권3호
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• pp.343-351
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• 2020

The present research deals with the multi-dual-phase-lags thermoelasticity theory for thermoelastic behavior of transversely isotropic thermoelastic thin circular plate The Laplace and Hankel transform techniques have been used to find the solution of the problem. The displacement components, stress components, and conductive temperature distribution are computed in the transformed domain with the radial distance and further determined in the physical domain using numerical inversion techniques. The effect of rotation and two temperature are depicted graphically on the resulting quantities.