• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.4
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• pp.125-132
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• 2015

PCI Express is high-speed point-to-point serial protocol, the system is designed by analysing loss and jitter through Eye Diagram. It is necessarily analyzing high speed serial signals when the PCI Express Gen3 which has 8Gbps physical signal speed is designed especially. This paper deals with topology extraction, channel analysis, extraction of s-parameters and system signal integrity simulation within transceiver buffer models through PCI Express Gen3 server connecting switch system design. Optimal parameters of transmitter buffer equalizer are found through solution space simulation of de-emphasis and preshoot parameters to compensate channel loss.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.10a
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• pp.190-195
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• 2000

This paper presents the fabrication of the LNA which is operating at 2.13∼2.16 GHz for IMT-2000 lot-end receiver using series feedback and resistive decoupling circuit. Series feedback added to the source lead of a transistor keep the low noise characteristics and drop the input reflection coefficient of amplifier simultaneously. Also, it increases the stability of the LNA. Resistive decoupling circuit is suitable for input stage matching because a signal at low frequency is dissipated by a resistor in the matching network The amplifier consist of GaAs FET ATF-10136 for low noise stage and VNA-25 which is internally matched MMIC for high gain stage. The amplifier is fabricated with both the RF circuits and self bias circuit on the Teflon substrate with 3.5 permittivity. The measured results of the LNA which is fabricated using above design technique are presented more than 30 dB in gain P$\_$ldB/ 17 dB and less than 0.7 dB in noise figure, 1.5 in input$.$output SWR(Standing Wave Ratio).

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.10
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• pp.29-35
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• 2009

This paper handles, implementation of multiple access bidirectional serial communications protocol using DC power lines. The normal voltage of the power communication line maintains 24[V] corresponding to level 1 and the host drops the voltage to 12[V] on sending level 0 signal, also the clients normally keeps the line voltage to 24[V] use pull-down circuit to drop the voltage to 12[V] on sending level 1 signal. Host senses the voltage level of the power communication lines and the hosts switches power source from 24[V] to 12[V]. Experimental circuit is designed with one hosts and four clients and verified the power line voltage switching operation depending on the data signal levels on the power line.

• Journal of KIISE:Databases
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• v.30 no.1
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• pp.95-107
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• 2003

The broadcast environment has asymmetric communication aspect that is typically much greater communication bandwidth available from server to clients than in the opposite direction. In addition, most of mobile computing systems allow mostly read-only transactions from mobile clients for retrieving different types of information such as stock data, traffic information and mews updates. Since previous concurrency control protocols, however, do not consider such a particular characteristics, the performance degradation occurs when previous schemes are applied to the broadcast environment. In this paper, we propose the efficient concurrency control for query transaction in broadcast environment. The following requirements are satisfied by adapting weak consistency that is the appropriate correctness criterion of read-only transactions: (1) the mutual consistency of data maintained by the server and read by clients (2) the currency of data read by clients. We also use the serialization graph scheme to check the weak consistency efficiently. As a result, we improved a performance by reducing unnecessary aborts and restarts of read-only transactions caused when global serializability was adopted.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.12
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• pp.42-49
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• 2016

This paper proposes a low-complexity generator which finds the first two minimum values using bit-serial scheme. A low-complexity generator is an important part for low-area LDPC decoders based on the min-sum decoding algorithm because the hardware complexity of generators utilizes a significant portion of LDPC decoders. To reduce hardware complexity, bit-serial LDPC decoders has been studied. The generator of the existing bit-serial LDPC decoders can find only the first minimum value, and thus it leads to a BER performance degradation. The proposed generator using bit-serial scheme finds the first two minimum values. Hence, it can improve the BER performance. In addition, the area-time complexity of the proposed generator is lower than those of the existing generators finding the first two minima.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.48 no.4
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• pp.142-152
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• 2011

In general, existing emergency evacuation guiding systems depend on visual techniques like emergency lights or LEDs. Actually people in the case of fire emergency condition may not obtain a range of view because of smoke from the fire. This paper introduces a technique to design an emergency guiding system using directivity sound to cope with this problem. In this case all speakers are serially connected for audio signal transmission in a serial fashion to achieve convenient speaker installation. Floyd algorithm is used to find shortest evacuation paths. Because serially connected multi-channel speakers are weak in case of disconnection, this paper uses a technique to solve the diagnostic problem. In the proposed system, a PC based on the USB protocol is used for control and observation. The system has achievements, such as increasing evacuation rate under emergency conditions, and serial transmission of audio signal for easy maintenance and low installation cost.

• Korean Journal of Optics and Photonics
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• v.17 no.1
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• pp.18-22
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• 2006

The transmission characteristics of multiply cascaded phase-shifted long-period fiber gratings(LPFGs) were investigated theo-retically and experimentally. Their passband can be changed by increasing the number of p-shifted LPFGs. When two p-shifted LPFGs with different grating lengths are cascaded in series, the bandwidth of the rejection band and passband can be controlled by the pristine characteristics of two gratings. We also investigate the transmission characteristics of phase-shifted LPFG by exposing the half of LPFG region to UV laser. The transmission characteristics strongly depend on the initial coupling strength of the LPFG.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.2
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• pp.49-54
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• 2008

In cryptosystems based on finite fields, a modular multiplication operation is the most crucial part of finite field arithmetic. Also, in multipliers with resource constrained environments, bit-serial output structures are used in general. This paper proposes two efficient bit-serial output multipliers with the polynomial basis representation for irreducible trinomials. The proposed multipliers have lower time complexity compared to previous bit-serial output multipliers. One of two proposed multipliers requires the time delay of $(m+1){\cdot}MUL+(m+1){\cdot}ADD$ which is more efficient than so-called Interleaved Multiplier with the time delay of $m{\cdot}MUL+2m{\cdot}ADD$. Therefore, in elliptic curve cryptosystems and pairing based cryptosystems with small characteristics, the proposed multipliers can result in faster overall computation. For example, if the characteristic of the finite fields used in cryprosystems is small then the proposed multipliers are approximately two times faster than previous ones.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.9
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• pp.9-17
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• 1999

In this paper, we present a mathematical modeling and perform a performance analysis of double-dwell serial search algorithm, which has a search window concept, for pilot channel in DS-CDMA(Direct Sequence Code Division Multiple Access). We derive a code detection function, a false alarm function, a code miss function, and a mean code acquisition time for the performance analysis. We calculate the mean code acquisition time of the mathematical model in IS-95 forward link and compare it with that of the conventional search methods. The performance of the code acquisition system is also evaluated to investigate the effect of dwell times and search window size. The JTC channel model, which is a PCS channel model in North America, is used for the analysis. The numerical result shows that the mean code acquisition time of the double-dwell serial search algorithm with a search window is reduced by about 17%~25% than those of the conventional ones.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.1A
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• pp.18-25
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• 2002

In this paper, the performance of three types of serial concatenated convolutional codes (SCCC) in AWGN (additive white Gaussian noise) channel is compared and analyzed. As results of simulations, it can be observed that Type I shows the best error performance at lower signal-to-noise ratio (SNR) region. However, Type III shows the best error performance at higher SNR region. It can be also observed the error floor that the performance cannot be improved even though increasing of the number of iterations and SNR at Type I. However, the performance of Type II and Type III are still improved over the five iterations at higher SNR without error floor. And BER performance of three types can be closed to upper bound of three types with increase of SNR. It can be also observed that the upper bound of Type III shows the best performance among the three types due to the greatest free distance.