• Journal of the Institute of Electronics Engineers of Korea SD
• /
• 제41권5호
• /
• pp.153-160
• /
• 2004

In this paper, we propose an efficient bit loading algorithm for IEEE 802.11a wireless LAN systems. While a conventional bit loading algorithm uses the SNR value of each subcarrier, it is very difficult to estimate the exact SNR value in wireless LAN systems due to randomness of AWGN. Therefore, in order to solve this problem our proposed algorithm uses the channel frequency response instead of the SNR of each subcarrier. Through simulation results, we can obtain the performance gain of 3.5∼8㏈ at PER of 10-2 with the proposed bit loading algorithm while the conventional one obtains the performance gain of 0.5∼5㏈ at the same conditions. Also, the increased data rate can be confirmed 63Mbps. After the logic synthesis using 0.3${\mu}{\textrm}{m}$ CMOS technology, the logic gate count for the processor with proposed algorithm can be reduced by 34% in comparison with the conventional one.

• The Transactions of the Korea Information Processing Society
• /
• 제3권7호
• /
• pp.1680-1686
• /
• 1996

The deterministic update method of intensional predicates in a parallel deductive database that deductive database is distributed in a parallel computer architecture in needed. Using updated data from the deterministic update method, a strategy for parallel evaluation of intensional predicates is required. The paper is concerned with an approach to updating parallel deductive database in which very insertion or deletion can be performed in a deterministic way, and an extended parallel semi-naive evaluation algorithm in a parallel computer architecture. After presenting an approach to updating intensional predicates and strategy for parallel evaluation, its implementation is discussed. A parallel deductive database consists of the set of facts being the extensional database and the set of rules being the intensional database. We assume that these sets are distributed in each processor, research how to update intensional predicates and evaluate using the update method. The parallel architecture for the deductive database consists of a set of processors and a message passing network to interconnect these processors.

• The Journal of the Acoustical Society of Korea
• /
• 제19권2호
• /
• pp.101-105
• /
• 2000

A telegram has been used to transmit the emergency news or celebration message. So, it has been very important media in our life. Although the telegram processing is more and more convenient, on the other hand, the telegram service contains only text message. The voice telegram is that delivering user's voice with text message. So, the voice telegram can be delivered sender's emotions and feelings. However, since voice information contains lots of data, large memory size and high cost processor are needed to deliver itself. In this paper, we proposed a new speech waveform coding method that has low complexity and low cost implementation for the voice telegram system. First, we fixed one basic speech waveform per pitch period and measured the waveform similarity between basic and neighbor speech waveform. Second, if the similarity satisfied threshold values, we compress the neighbor speech waveform with pitch and magnitude value per pitch period and if not, we save speech waveform. When the compression is about 45%, we obtained about 4 point in MOS.

• Journal of Biosystems Engineering
• /
• 제26권3호
• /
• pp.287-294
• /
• 2001

The geometrical and physical properties of red peppers were studied for proper design of a red pepper processor. Mass, volume, roundness and compactness of red peppers were calculated from digital images. They were compared with real data and the relations of them were suggested. Roundness of red peppers was ranged from 0.2 to 0.5 and the average value was 0.349. Compactness of red peppers was ranged from 25 to 50 and the average value was 37.1. The regression equations to calculate the volume and mass of red pepper were obtained as y$\_$v/$\_$=/0.553$\varkappa$$_1$+1.441$\varkappa$$_2$-1.013$\varkappa$$_3$(R=0.95) and y$\_$m/=0.252$\varkappa$$_1$+0.938$\varkappa$$_2$-0.499$\varkappa$$_3$-1.5112 (R=0.93), y$\_$v/:volume(㎤), y$\_$m/:mass(g), $\varkappa$$_1$: perimeter(cm), $\varkappa$$_2$: area(㎠), $\varkappa$$_3$: length of major axis(cm), respectively. The direction for aligning the red pepper in a machine processing was easily and perfectly recognized. The response time for digital image processing has to be reduced for more efficient operation. HSI and YIQ values could be useful for recognizing the red pepper from background.

• Journal of KIISE:Computer Systems and Theory
• /
• 제34권11호
• /
• pp.581-588
• /
• 2007

In Digital Right Management, symmetric cipher is used for content encryption to reduce encryption cost, AES, advanced encryption standard is usually used to multimedia encryption under desktop environment because of its reasonable security level and computation cost. But mobile handheld device often uses slow speed processor and operates under battery-powered environment. Therefore it requires low computation cost and low energy consumption. This paper proposes new stream cipher scheme which combines pseudo random number generator(PRNG) and dynamically generated permutations. Proposed scheme activates PRNG and generates original key streams. Then it generates extended key streams by applying permutation to original sequence. These extended key streams are XORed with plaintext and generate ciphertext. Proposed scheme reduces the usage of PRNG. Therefore this scheme is fast and consumes less energy in comparison with normal stream cipher. Especially, this scheme shows great speed up (almost 2 times) than normal stream cipher scheme in random access.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• 제25권4호
• /
• pp.749-757
• /
• 2015

As the smart era, the use of smart devices is increasing. Smart devices are widely used to provide a human convenience, but there is a risk that information is exposed. The smart devices to prevent this problem includes the encryption algorithm. Among them, The hash function is an encryption algorithm that is used essentially to carry out the algorithm, such as data integrity, authentication, signature. As the issue raised in the collision resistance of SHA-1 has recently been causing a safety problem, and SHA-1 hash function based on the current standard of SHA-2 would also be a problem in the near future safety. Accordingly, NIST selected KECCAK algorithm as SHA-3, it has become necessary to implement this in various environments for this algorithm. In this paper, implementation of KECCAK algorithm. And SHA-2 On The ARM-11 processor, and compare performance.

• Journal of the Korean Society for Nondestructive Testing
• /
• 제14권2호
• /
• pp.101-111
• /
• 1994

Electronic speckle pattern interferometry(ESPI) using a CW laser, a video system and an image processor were applied to the in-plane displacement measurements. Unlike traditional strain gauges or Moire method, ESPI method requires no special surface preparation or attachments and it can be measured in-plane displacement without any contact and real time. In this experiment, specimen was loaded in paralled with a loa cell. The specimen was plance to which strain gauges was attached. The study provides an example of how ESPI have been used to measure displacement and strain distribution in this specimen. The results measured by ESPI were compared with the data which were measured by strain gauge method in tensile testing.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• 제35권10호
• /
• pp.940-947
• /
• 2007

For the performance upgrade of a supersonic jet fighter, the processor and FLCC(Flight Control Computer) Architecture were upgraded from a baseline FLCC. Prior to the hardware implementation phase, the exact CPU throughput estimation is necessary. For this purpose, an experimental method for new FLCC throughput estimation was introduced in this study.　While baseline FLCC operating, the CPU address bus was collected with logic analyzer, and then decoded to get the exact access times to each memory-memory and the number of program Instruction branches. Based on these data, a throughput test in CPU demo-board of the new FLCC configuration was performed. From test results, the CPU-Memory architecture was design-changed before FLCC hardware implementation phase. To check the flight stability degradation due to power-interrupt problem due to CPU-Memory architecture change, the piloted HILS (Hardware-In-the Loop Simulator) test was conducted.

• Journal of Energy Engineering
• /
• 제19권2호
• /
• pp.128-135
• /
• 2010

This paper introduces step by step procedures for the fabrication and operation of an embedded solar tracker. The system presented consists of application software, compactRIO, C-series interface module, analogue input module, step drive, step motor, feedback devices and other accessories to support its functional stability. CompactRIO that has a real-tim processor allows the solar tracker to be a stand-alone real time system which operates automatically without any external control. An astronomical method and an optical method were used for a high-precision solar tracker. CdS sensors are used to constantly generate feedback signals to the controller, which allow a solar tracker to track the sun even under adverse conditions. The database of solar position and sunrise and sunset time was compared with those of those of the Astronomical Applications Department of the U.S. Naval Observatory. The results presented here clearly demonstrate the high-accuracy of the present system in solar tracking, which are applicable to many existing solar systems.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제8권10호
• /
• pp.3475-3489
• /
• 2014

Here we present a simple flame detection method for an infrared (IR) thermal camera based real-time fire surveillance digital signal processor (DSP) system. Infrared thermal cameras are especially advantageous for unattended fire surveillance. All-weather monitoring is possible, regardless of illumination and climate conditions, and the data quantity to be processed is one-third that of color videos. Conventional IR camera-based fire detection methods used mainly pixel-based temporal correlation functions. In the temporal correlation function-based methods, temporal changes in pixel intensity generated by the irregular motion and spreading of the flame pixels are measured using correlation functions. The correlation values of non-flame regions are uniform, but the flame regions have irregular temporal correlation values. To satisfy the requirement of early detection, all fire detection techniques should be practically applied within a very short period of time. The conventional pixel-based correlation function is computationally intensive. In this paper, we propose an IR camera-based simple flame detection algorithm optimized with a compact embedded DSP system to achieve early detection. To reduce the computational load, block-based calculations are used to select the candidate flame region and measure the temporal motion of flames. These functions are used together to obtain the early flame detection algorithm. The proposed simple algorithm was tested to verify the required function and performance in real-time using IR test videos and a real-time DSP system. The findings indicated that the system detected the flames within 5 to 20 seconds, and had a correct flame detection ratio of 100% with an acceptable false detection ratio in video sequence level.