• KSII Transactions on Internet and Information Systems (TIIS)
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• v.3 no.6
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• pp.612-627
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• 2009

The high-level contribution of this paper is to illustrate the effectiveness of using graph theory tree traversal algorithms (pre-order, in-order and post-order traversals) to generate the chain of sensor nodes in the classical Power Efficient-Gathering in Sensor Information Systems (PEGASIS) data aggregation protocol for wireless sensor networks. We first construct an undirected minimum-weight spanning tree (ud-MST) on a complete sensor network graph, wherein the weight of each edge is the Euclidean distance between the constituent nodes of the edge. A Breadth-First-Search of the ud-MST, starting with the node located closest to the center of the network, is now conducted to iteratively construct a rooted directed minimum-weight spanning tree (rd-MST). The three tree traversal algorithms are then executed on the rd-MST and the node sequence resulting from each of the traversals is used as the chain of nodes for the PEGASIS protocol. Simulation studies on PEGASIS conducted for both TDMA and CDMA systems illustrate that using the chain of nodes generated from the tree traversal algorithms, the node lifetime can improve as large as by 19%-30% and at the same time, the energy loss per node can be 19%-35% lower than that obtained with the currently used distance-based greedy heuristic.

• Transactions on Electrical and Electronic Materials
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• v.7 no.1
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• pp.42-50
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• 2006

Co-Fe-Al-O nano-granular thin films with high electrical resistivity, fabricated by radio frequency magnetron sputtering under an $Ar+O_2$ atmosphere, are found to show good soft magnetic properties in the GHz frequency range. The real part value of the relative permeability is 260 at low frequencies and this value is maintained up to the GHz frequency range. A non-integrated type noise filter on a coplanar waveguide transmission line is demonstrated by using the Co-Fe-Al-O nano-granular thin film with the dimensions of $4\;mm(l){\times}4\;mm(w){\times}0.1\;{\mu}m(t)$. The insertion loss is very low being less than 0.3 dB and this low value is maintained up to 2 GHz. At a ferromagnetic resonance frequency of 3.3 GHz, the degree of noise suppression is measured to be 3 dB. This level of noise attenuation is small for real applications, but there is much room for further improvement by increasing the magnetic volume and integrating the magnetic thin film into the CPW transmission line.

• Journal of the Korean Society of Safety
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• v.27 no.2
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• pp.92-97
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• 2012

Risk management is the process that helps to identify hazards, analyze them, and then to create an action plan to avoid and mitigate these hazards. The main objective of risk management in product development and manufacturing is to provide safe and efficient products without spending too many resources. Medical device manufacturers also face enormous risks - regulatory, legal, and financial - based on their products and processes, and the concepts of risk management are particularly important because any single failure may result in serious damages to body or loss of life. In this regard, a set of guidelines for the application of risk management to medical devices has been issued by ISO and specified in the document ISO 14971 Medical devices - Application of risk management to medical devices. The main objective of this study is to investigate the application of risk management to dental implant development and manufacturing processes based on ISO 14971. A general risk management process is first introduced, and the application of ISO 14971 to dental implants is further investigated.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.3226-3236
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• 2011

In this paper, with the background features on which measuring the transverse left-right and up -down vibration of wheel, bogie and body by wireless measurement system, performance evaluation systems which can assess the running behavior of high speed trains based on UIC code 518-OR and evaluate the ride comfort of them based on ISO code 2631 and UIC code 513 were developed. The characteristics of dynamic vibration are generally analyzed by an acceleration of a car body of high speed train and the acceleration can be applied to evaluation of running safety. In this paper, also matching system of distance from tachometer and vibration from accelerometer was programmed in development software, and the SD card embedded system which prevent to loss of data in wireless measurement was mounted on this system. Finally the software perform to analysis with filtering and statistical post-process in the unit sections and zones and focus on developing the capability monitoring in the main control center. For the verification of this system, the running behavior and safety factor were analyzed based on field measured data of the Cheonjun-gunnum-sun turn out point in the new KTX railway.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.6
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• pp.71-76
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• 2010

In this paper, a 120 GHz local oscillator(LO) for the sub-harmonic mixer in the THz transceiver with a carrier frequency of 240 GHz was designed and fabricated. A 120 GHz local oscillator was composed of 40 GHz PLL(Phase Locked Loop), 40 GHz BPF(Band Pass Filter), frequency tripler and 120 GHz BPF. The commercial model of the frequency tripler was used. The measured result of the 40 GHz PLL showed the phase noise of -105 dBc/Hz at the 100 kHz offset frequency. The measured result of 120 GHz BPF showed the insertion loss of 1.3 dB at center frequency of 119 GHz with bandwidth of 5 GHz. The output power of 120 GHz LO was measured to 6.6 dBm.

• Computers and Concrete
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• v.8 no.2
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• pp.177-192
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• 2011

This research paper aims at computer based modeling of carbonation induced corrosion under extreme conditions and its experimental verification by incorporating enhanced electrochemical and mass balance equations based on thermo-hygro physics with strong coupling of mass transport and equilibrium in micro-pore structure of carbonated concrete for which the previous research data is limited. In this paper the carbonation induced electrochemical corrosion model is developed and coupled with carbon dioxide transport computational model by the use of a concrete durability computer based model DuCOM developed by our research group at concrete laboratory in the University of Tokyo and its reliability is checked in the light of experiment results of carbonation induced corrosion mass loss obtained in this research. The comparison of model analysis and experiment results shows a fair agreement. The carbonation induced corrosion model computation reasonably predicts the quantitative behavior of corrosion rate for normal air dry relative humidity conditions. The computational model developed also shows fair qualitative corrosion rate simulation and analysis for various pH levels and coupled environmental actions of chloride and carbonation. Detailed verification of the model for the quantitative carbonation induced corrosion rate computation under varying relative conditions, different pH levels and combined effects of carbonation and chloride attack remain as scope for future research.

• Wind and Structures
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• v.14 no.5
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• pp.435-447
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• 2011

A Computational Fluid Dynamics model is presented in this study for the simulation of the complex fluid flows with free surfaces inside the Tuned Liquid Column Dampers in horizontal motion. The characteristics of the fluid model of the TLCD in horizontal motion include the free surface of the multiphase flow and the horizontal moving frame. In this study, the time depend unsteady Standard ${\kappa}-{\varepsilon}$ turbulent model based on Navier-Stokes equations is chosen. The volume of fluid (VOF) method and sliding mesh technique are adopted to track the free surface of water inside the vertical columns of TLCD and treat the moving boundary of the walls of TLCD in horizontal motion. Several model solution parameters comprising different time steps, mesh sizes, convergence criteria and discretization schemes are examined to establish model parametric independency results. The simulation results are compared with the experimental data in the dimensionless amplitude of the water column in four different configured groups of TLCDs with four different orifice areas. The predicted natural frequencies and the head loss coefficient of TLCDs from CFD model are also compared with the experimental data. The predicted numerical results agree well with the available experimental data.

• BMB Reports
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• v.49 no.2
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• pp.69-70
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• 2016

Mutations of orthodentricle homeobox 2 (OTX2) in human and mice often cause retinal dystrophy and nyctalopia, suggesting a role of OTX2 in mature retina, in addition to its functions in the development of the eye and retina. In support of this, the number of bipolar cells in Otx2^+/− post-natal mouse retina was found to be significantly lower than normal. Degeneration of the cells becomes greater as the mice age, leading to the loss of vision. Especially, the type-2 OFF-cone bipolar cells, which do not express Otx2 mRNA but carry Otx2 protein, are most sensitive to Otx2 haplodeficiency. Interestingly, this bipolar cell subpopulation imports Otx2 protein from photoreceptors to protect itself from glutamate excitotoxicity in the dark. Moreover, in the bipolar cells, the exogenous Otx2 relocates to the mitochondria to support mitochondrial ATP synthesis. This novel mitochondrial activity of exogenous Otx2 highlights the therapeutic potential of Otx2 protein transduction in retinal dystrophy.

• Earthquakes and Structures
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• v.7 no.2
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• pp.201-216
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• 2014

In this paper the vulnerability of the confined masonry buildings is evaluated analytically. The proposed approach includes the nonlinear dynamic analysis of the two-story confined masonry buildings with common plan as a reference structure. In this approach the damage level is calculated based on the probability of exceedance of loss vs a specified ground motion in the form of fragility curves. The fragility curves of confined masonry wall buildings are presented in two levels of limit states corresponding to elastic and maximum strength versus PGA based on analytical method. In this regard the randomness of parameters indicating the characteristics of the building structure as well as ground motion is considered as likely uncertainties. In order to develop the analytical fragility curves the proposed analytical models of confined masonry walls in a previous investigation of the authors, are used to specify the damage indices and responses of the structure. In order to obtain damage indices a series of pushover analyses are performed, and to identify the seismic demand a series of nonlinear dynamic analysis are conducted. Finally by considering various mechanical and geometric parameters of masonry walls and numerous accelerograms, the fragility curves with assuming a log normal distribution of data are derived based on capacity and demand of building structures in a probabilistic approach.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.8
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• pp.849-856
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• 2014

This paper proposes a new efficient CFAR algorithm. The structure of the proposed CFAR is relatively simple as compared with the OS-CFAR or ML-CFAR which are considered to deal with the nonhomogeneous environment such as clutter and multiple targets. The proposed algorithm is effectively applied to the radar signal processor with reduced computation burden. The relationship between the threshold and PFA of the proposed CFAR is derived analytically. The CFAR loss of the proposed CFAR algorithm is compared with CA-CFAR and OS-CFAR based on both SNR and ADT(Average Detection Threshold).