• Journal of Internet Computing and Services
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• v.7 no.1
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• pp.143-150
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• 2006

The quickest path problem deals with the transmission of a message of size ${\sigma}$ from a source to a destination with the minimum end to end delay over a network with bandwidth and delay constraints on the links. We consider two basic modes and four variations for the message delivery at the nodes reflecting the mechanisms such as circuit switching. Internet protocol, and their combinations, For each of first five modes, we present O($m^2+mnlogn$) algorithm to compute the quickest path for a given message size ${\sigma}$, For the last mode, the quickest path can be computed in O(m+nlogn) time.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.10
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• pp.5035-5057
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• 2019

Advancements in nanotechnology and novel nano materials in the past decade have provided a set of tools that can be used to design and manufacture integrated nano devices, which are capable of performing sensing, computing, data storing and actuation. In this paper, we have proposed cooperative nano communication using Power Switching Relay (PSR) Wireless Power Transfer (WPT) protocol and Time Switching Relay (TSR) WPT protocol over independent identically distributed (i.i.d.) Rayleigh fading channels in the Terahertz (THz) Gap frequency band to increase the range of transmission. Outage Probability (OP) performances for the proposed cooperative nano communication networks have been evaluated for the following scenarios: A) A single decode-and-forward (DF) relay for PSR protocol and TSR protocol, B) DF multi-relay network with best relay selection (BRS) for PSR protocol and TSR protocol, and C) DF multi-relay network with multiple DF hops with BRS for PSR protocol and TSR protocol. The results have shown that the transmission distance can be improved significantly by employing DF relays with WPT. They have also shown that by increasing the number of hops in a relay the OP performance is only marginally degraded. The analytical results have been verified by Monte-Carlo simulations.

• Korean Journal of Optics and Photonics
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• v.9 no.6
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• pp.417-422
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• 1998

In this paper we introduce a method to optimize panel parameters and drive signals in a matrix-adressed bistable twsited-nematic (BTN) liquid crystal display (LCD) panel. We measured the effect of data pulses on optical switching characteristics in a BTN LC cell to model the effect theoretically. We introduce a weighting function to model the effect of data pulses on the switching energy as a function of time. Once the weighting function is known, we can estimate the maximum number of lines for multiplexing operation at a given frame rate by calculating the minimum data pulse width. By characterizing a unit cell as we change panel parameters (for example, d/p ratio), we can optimize parameters for high-speed operation. We found that our theoretical predictions agree very well with experimental results.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.3
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• pp.639-650
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• 1999

In this paper, a chattering alleviation VSS controller for the sinusoidal type BLDC motor is designed. Dead Zone function is proposed to change the chattering occurring in the transient state from high frequency to low frequency and time-varying gains are applied for the control input to eliminate the steady state excessive chattering in the conventional ISM. The proposed Dead Zone function represents the sliding layer composed of two switching surfaces and if a state vector exists in this layer, the chattering don't occur. Simulation and experimental results confirm the useful effects of the above algorithm.

• Journal of Power Electronics
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• v.16 no.6
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• pp.2231-2242
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• 2016

A simplified model predictive control method is presented in this paper. This method is based on a future reference voltage vector for a three-phase four-leg voltage source inverter (VSI). Compared with the three-leg VSIs, the four-leg VSI increases the possible switching states from 8 to 16 owing to a fourth leg. Among the possible states, this should be considered in the model predictive control method for selecting an optimal state. The increased number of candidate switching states and the corresponding voltage vectors increase the calculation burden. The proposed technique can preselect 5 among the 16 possible voltage vectors produced by the three-phase four-leg voltage source inverters, based on the position of the future reference voltage vector. The discrete-time model of the future reference voltage vector is built to predict the future movement of the load currents, and its position is used to choose five preselected vectors at every sampling period. As a result, the proposed method can reduce calculation load by decreasing the candidate voltage vectors used in the cost function for the four-leg VSIs, while exhibiting the same performance as the conventional method. The effectiveness of the proposed method is demonstrated with simulation and experiment results.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.1015-1016
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• 2006

The important parameters deciding the fluctuation of Accumulation style surgical operation of ventriculus laser beam are smoothing capacitor, frequency and he characteristics of laser resonator. In this thesis, we control the fluctuation of medical $CO_2C$ laser in realtime by changing Duty-Ratio of IGBT and switching frequency with fixed the smoothing capacitor to improve the fluctuation of laser beam. We detect the light on laser resonator using a CdS photo sensor to improve ripple factor of laser beam and feedback fluctuated signals refined by a band pass filter into the control circuit to stabilize fluctuation actively. There is much to be desired in the realtime controlling technique of the light on Accumulation style surgical operation of ventriculus laser discharge tube in electrical signal. We propose switching control technique with microprocessor and photo sensing technique by controlling switch devices optimum operation and feedback signals detected by a photo sensor into the laser power supply in order to improve ripple factor of the $CO_2$ laser beam.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.4
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• pp.405-414
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• 2016

IC-implementations provide high performance for solving the high computational cost of pattern matching but have relative low flexibility for satisfying different applications. In this paper, we report an associative memory architecture for k nearest neighbor (KNN) search, which is one of the most basic algorithms in pattern matching. The designed architecture features reconfigurable vector-component parallelism enabled by programmable switching circuits between vector components, and a dedicated majority vote circuit. In addition, the main time-consuming part of KNN is solved by a clock mapping concept based weighted frequency dividers that drastically reduce the in principle exponential increase of the worst-case search-clock number with the bit width of vector components to only a linear increase. A test chip in 180 nm CMOS technology, which has 32 rows, 8 parallel 8-bit vector-components in each row, consumes altogether in peak 61.4 mW and only 11.9 mW for nearest squared Euclidean distance search (at 45.58 MHz and 1.8 V).

• Journal of electromagnetic engineering and science
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• v.11 no.4
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• pp.239-249
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• 2011

In this paper, we propose a reliable $8{\times}8$ up-down switching polar relay code based on 3GPP LTE standard, motivated by 3GPP LTE down link, which is 30 bps/Hz for $8{\times}8$ MIMO antennas, and by Arikan's channel polarization for the frequency selective fading (FSF) channels with the generator matrix $Q_8$. In this scheme, a polar encoder and OFDM modulator are implemented sequentially at both the source node and relay nodes, the time reversion and complex conjugation operations are separately implemented at each relay node, and the successive interference cancellation (SIC) decoder, together with the cyclic prefix (CP) removal, is performed at the destination node. Use of the scheme shows that decoding at the relay without any delay is not required, which results in a lower complexity. The numerical result shows that the system coded by polar codes has better performance than currently used designs.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.4A
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• pp.399-414
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• 2004

In this paper, an evolution of software reliability engineering in a large-scale software project is summarized. The considered software consists of many components, called functional blocks in software of switching system. These functional blocks are served as the unit of coding and test, and the software is continuously updated by adding new functional blocks. We are mainly concerned with the analysis of the effects of these software components in software reliability and reliability evolution. We analyze the static characteristics of the software related to software reliability using collected failure data during system test. We also discussed a pattern which represents a local and global growth of the software reliability as version evolves. To find the pattern of system software, we apply the S-shaped model to a collection of failure data sets of each evolutionary version and the Goel-Okumoto(G-O) model to a grouped overall failure data set. We expect this pattern analysis will be helpful to plan and manage necessary human/resources fur a new similar software project which is developed under the same developing circumstances by estimating the total software failures with respect to its size and time.

• ETRI Journal
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• v.38 no.1
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• pp.18-29
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• 2016

In this paper, we discuss the issues of providing protection for point-to-multipoint connections in both Ethernet and MPLS-TP-based packet transport networks. We introduce two types of per-leaf protection-linear and ring. Neither of the two types requires that modifications to existing standards be made. Their performances can be improved by a collective signal fail mechanism proposed in this paper. In addition, two schemes - tree protection and hybrid protection - are newly proposed to reduce the service recovery time when a single failure leads to multiple signal fail events, which in turn places a significant amount of processing burden upon a root node. The behavior of the tree protection protocol is designed with minimal modifications to existing standards. The hybrid protection scheme is devised to maximize the benefits of per-leaf protection and tree protection. To observe how well each scheme achieves an efficient traffic recovery, we evaluate their performances using a test bed as well as computer simulation based on the formulae found in this paper.