• Progress in Superconductivity
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• v.7 no.1
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• pp.36-40
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• 2005

The problem of fluctuation-induced digital errors in a rapid single flux quantum (RSFQ) circuit has been a very important issue. In this work, we calculated the bit error rate of an RSFQ switch used in superconductive arithmetic logic unit (ALU). RSFQ switch should have a very low error rate in the optimal bias. Theoretical estimates of the RSFQ error rate are on the order of $10^{-50}$ per bit operation. In this experiment, we prepared two identical circuits placed in parallel. Each circuit was composed of 10 Josephson transmission lines (JTLs) connected in series with an RSFQ switch placed in the middle of the 10 JTLs. We used a splitter to feed the same input signal to both circuits. The outputs of the two circuits were compared with an RSFQ exclusive OR (XOR) to measure the bit error rate of the RSFQ switch. By using a computerized bit-error-rate test setup, we measured the bit error rate of $2.18{\times}10^{-12}$ when the bias to the RSFQ switch was 0.398 mA that was quite off from the optimum bias of 0.6 mA.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.2
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• pp.43-51
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• 1997

In this paper, we quantize the image data to simplify the systolic array architecture for block matching algorithm. As the number of bits for pixel data to be processed is reduced by quantization, one can simplify the hardware of systolic array. Especially, if the bit serial input is used, one can even more simplify the structure of processing element. First, we analize the effect of quantization to a block matching. then we show the structure of quantizer and processing element when bit serial input is used. The simulation results applied to standard images have shown that the proposed block matching method has less prediction error than the conventional high speed algorithm.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.6
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• pp.868-874
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• 2002

A high-impulse, low-power, digital microthruster has been developed using low-boiling-temperature liquid propellant with high-viscosity fluid plug. The viscous fiction force of the fluid plug increases the blast pressure and the low-boiling-temperature liquid propellant is intended to reduce input power consumption. The three-layer microthruster has been fabricated by surface micromachining as well as bulk micromachining in the size of 7$\times$13$\times$1.5㎣. A digital output impulse bit of 6.4$\times$10$^{-8}$ Nsec has been obtained from the fabricated microthruster using perfluoro normal hexane (FC72) propellant and oil plug, resulting in about ten times increase of the impulse bit using one hundredth electrical input energy compared to the conventional multiple-shot microthruster.

• Proceedings of the KSME Conference
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• 2001.06c
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• pp.59-63
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• 2001

A high-impulse, low-power, continuous-shot microthruster has been developed using low boiling temperature liquid-propellant with high viscous fluid-plug. The viscous friction force of the fluid-plug increases the blast pressure and the low boiling temperature liquid-propellant is intended to reduce input power consumption. The three-layer microthruster has been fabricated by surface micromachining as well as bulk micromachining in the size of $7{\times}13{\times}1.5mm^{3}$. A continuous output impulse bit of $6.4{\times}10^{-8}N{\cdot}sec$ has been obtained from the fabricated microthruster using perfluoro normal hexane (FC72) propellant and oil plug, resulting in about ten times increase of the impulse bit using one hundredth electrical input energy compared to the conventional continuous microthruster.

• 전자공학회논문지 IE
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• v.43 no.2
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• pp.16-21
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• 2006

In this paper we proposed of the SEED cipher algorithm which improved cipher intensity. The proposed algorithm has input data of 192bit and key input data of 256bit and it performs 16 Rounds for improvement of cipher intensity. We simulated the algorithm employing C compiler and the Foundation Express Tool so that verified performance of it.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1997.06a
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• pp.19-24
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• 1997

This paper describes an image segmentation technique for the object-oriented coding at very low bit rates. By noting that, in the object-oriented coding technique, each objects are represented by 3 parameters, namely, shape, motion, and color informations, we propose a segmentation technique, in which the 3 parameters are fully exploited. To achieve this goal, starting with the color space conversion and the noise reduction, the input image is divided into many small regions by the K-menas algorithm on the O-K-S color space. Then, each regions are merged, according to the shape and motion information. In simultations, it is shown that the proposed technique segments the input image into relevant objects, according to the shape and motion as well as the colors. In addition, in order to evaluate the performance of the proposed technique, we introduce the notion of the interesting regions, and provide the results of encoding the image with emphasizing the interesting regions.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.1
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• pp.101-114
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• 1991

In a DES-like cryptosystem, the S(ubstitution) boxes determine its cryptographic strength as well as its nonlinearity. When in an S box a part of the output depends on a part of the input. It can be broken by the chosen plaintext attack. To prevent this attack, every output bit should changes with a probability of one half when ever a single input bit is complemented. We call this criterion Strict Avalanche criterion(SAC), which was proposed by Webster and Tavared. In this paper, we propose simple construction method of Boolean functions satisfying the SAC and bijective functions satisfying the maximum order SAC in order to design cryptographically desirable S-boxes. Also, practical construction examples of S-boxes are provided.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.7
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• pp.1577-1582
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• 2013

In this paper, we have analyzed the performance of MIMO (Multi-Input Multi-Output) underwater acoustic communication by using the acquired data via the experiments in water tank. First of all, in the pursuit of this aim, we have measured the channel transfer characteristics at several transceiver locations. The transmitted signal was modulated by QPSK(Quadrature Phase Shit Keying) and the received signal was recovered through the detector that contains the zero forcing equalizer. A maximum 30~40 ms delay was appeared because of physically closed water tank environment that has the harsh multi-path transmission conditions. In result of experiment, even though the bit error rate showed comparatively large when $2{\times}2$ MIMO system with two transmitters and receivers was considered. However, we confirmed it has approximately 15% enhanced performance compared with SISO (Single-Input Single-Output) system.

• Proceedings of the IEEK Conference
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• 2000.06c
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• pp.85-88
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• 2000

This paper describes the design of multiplier that receives two N-bit number and produces an N-bit product, with leading 0/l detector logic for an overflow prediction. A leading 0/l detector for two's input predict a scope of output. The part of partial products sum of N most-significant bits is exchanged for an overflow prediction. Therefore this multiplier requires less gates for the implementation about 45% than general multipliers.

• Journal of the Korean Institute of Intelligent Systems
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• v.2 no.2
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• pp.42-60
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• 1992

An adaptive fuzzy system can efficiently classify subimages into four categories according to image activity level for image data compression. The system estimates fuzzy rules by clustering input-output data generated from a given adaptive transform image coding process. The system encodes different images without modification and reduces side information when encoding multiple images. In the second part, a fuzzy system estimates optimal bit maps for the four subimage classes in noisy channels assuming a Gauss-Markov image model. The fuzzy systems respectively estimate the sampled subimage classification and the bit-allocation processes without a mathematical model of how outputs depend on inputs and without rules articulated by experts.