• Proceedings of the Korean Information Science Society Conference
• /
• 2001.04a
• /
• pp.850-852
• /
• 2001

Fragile 워터마킹은 이미지의 무결성을 보장하기 위하여 원본 이미지에 사람이 지각할 수 없는 데이터를 삽입하는 것을 말한다. 본 논문은 이진 데이터의 삽입이 가능하며, 원본 이미지와 삽입된 데이터의 무결성이 보장되는 fragile 워터마킹의 한 방법을 제시한다. 제시된 방법은 hash 함수와 PRBG(pseudo random bit generator)를 이용한 one-time pad를 사용하며, 한 pixel당 약 2.8125bits의 정보를 저장할 수 있다.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.33 no.2
• /
• pp.62-69
• /
• 1984

In this paper we present a microprocessor-based interpolator using algebraic arithmetic method. The interpolator consists of 2900 "bit-slice" microprocessor chips and 0.5K ROMs of 36-bit microprogram memory. The system design is an instuction-data-based architecture with 250ns cycle time. A significant feature of the interpolator is that it has flexibility, very fast interpolation speed of 250 K pulses/sec, and performs additional functions simultaneously. Throughout the paper detailed explanations are given as to how one can design the hardware and software, and experimental results are presented.presented.

• Journal of KIISE:Computing Practices and Letters
• /
• v.13 no.6
• /
• pp.397-401
• /
• 2007

Recent applications on continuous queries on moving objects are extended quickly to various parts. These applications need not only 2-dimensional space data but also high-dimensional space data. If we use previous index for overlapped continuous range queries on high-dimensional space data, as the number of continuous range queries on a large number of moving objects becomes larger, their performance degrades significantly. We focus on stationary queries, non-exponential increase of storage cost and efficient processing time for large data sets. In this paper, to solve these problems, we present a novel query indexing method, denoted as PAB(Projected Attribute Bit)-based query index. We transfer information of high-dimensional continuous range query on each axis into one-dimensional bit lists by projecting technique. Also proposed query index supports incremental update for efficient query processing. Through various experiments, we show that our method outperforms the CES(containment-encoded squares)-based indexing method which is one of the most recent research.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2015.10a
• /
• pp.834-837
• /
• 2015

In this paper, we designed the FPGA hardware-based real-time ECG simulator, which generates an analog ECG signal within the range of 0 to 5 volts and described function. The ECG signal generated by the simulator can be applied to laboratory tests, the medical device, and the calibration study in various ways. ECG signals generated by simulator are obtained with conventional 24bit quantization to generate the signal data, and they are sampled and quantized to 1kHz of the 8-bit resolution when used as actual data. The proposed simulator is implemented using xilix Spartan-3 and data are transmitted through an RS-232 between the PC and the FPGA simulator. The transmitted data are stored in the memory and the stored data are printed out with the analog ECG signal through DAC (0808). It can also control the heart rate (HR) via the two buttons level UP-DOWN. We used existing ECG input rating for the evaluation of the designed system and evaluated differential circuit for obtaining QRS waveform and the output signal. We finally could obtained proper the result.

• Journal of Communications and Networks
• /
• v.15 no.6
• /
• pp.559-568
• /
• 2013

We report on the first error-free terahertz (THz) wireless communication at 0.310 THz for data rates up to 8.2 Gbps using a 18-GHz-bandwidth GaAs/AlGaAs field-effect transistor as a detector. This result demonstrates that low-cost commercially-available plasma-wave transistors whose cut-off frequency is far below THz frequencies can be employed in THz communication. Wireless communication over 50 cm is presented at 1.4 Gbps using a uni-travelling-carrier photodiode as a source. Transistor integration is detailed, as it is essential to avoid any deleterious signals that would prevent successful communication. We observed an improvement of the bit error rate with increasing input THz power, followed by a degradation at high input power. Such a degradation appears at lower powers if the photodiode bias is smaller. Higher-data-rate communication is demonstrated using a frequency-multiplied source thanks to higher output power. Bit-error-rate measurements at data rates up to 10 Gbps are performed for different input THz powers. As expected, bit error rates degrade as data rate increases. However, degraded communication is observed at some specific data rates. This effect is probably due to deleterious cavity effects and/or impedance mismatches. Using such a system, realtime uncompressed high-definition video signal is successfully and robustly transmitted.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.21 no.3
• /
• pp.370-378
• /
• 2018

The mission data in missile systems should be quickly and reliably transmitted from a mission transmission device to a guidance control unit. The MIL-STD-1553B is one of the reliable communication standards, but its bit rate is generally limited to 1Mbps due to the intrinsic properties of its electrical design. Therefore, the bus controller needs to be optimized to efficiently transmit the mission data on the inevitably limited bit rate. This paper proposes an analytical approach based on sampling-based optimization methods to maximize the data throughput without data loss. The proposed approach was evaluated in the simulations with the data transmission model for the MIL-STD-1553B communication system. The results of the proposed methods were applied to a real-time system and showed that the proposed method was successfully performed.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.27 no.6C
• /
• pp.594-600
• /
• 2002

A data manipulation unit capable of bit partitioned shift and various multimedia data type conversions in addition to conventional shift, is presented. Utilizing the similarity between the data type conversion and the shift, the addition of small amount of interconnections to conventional barrel shifter enables data type conversion as well as shift operations with minimal hardware overhead. The presented data manipulation unit is composed of the shifter block for conventional shift and a pack and a unpack block. It has been designed with verilog HDL and the VLSI implementation results using compass 0.6 um standard cell are discussed.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.16 no.2
• /
• pp.162-171
• /
• 1991

This paper presents an algorithm for compressing image data by separating the image into two parts. I.e. edge image containing high-frequency components and non-edge image containing low-frequency components of image. The edge image is extracted by using 8 level compass gradient masks and the non-edge image is obtained by removing the edge image from the original image. The edge image is coded by Huffman run-length code and the non edge image is transformed first by DCT and the transformed images is coded next by a quantized bit allocation table. For an example image. GIRL. the proposed algorithm shows bit rate of 0.52 bpp with PSNR of 36dB.

• Journal of Broadcast Engineering
• /
• v.6 no.1
• /
• pp.41-49
• /
• 2001

Digital watermarking has been proposed for copyright protection of digital data. According to the property of an embedded watermark, it is classified into two categories, robust watermarking and fragile watermarking. The former is used for copyright protection, and the latter applies to the authentication/integrity to verify the authenticity of data, If an Image has been modified or forged. the embedded watermark cannot be extracted from the Image. As a results, it is possible to defect the modification of the image. As pixels are represented by tilts, the modification of bits corresponds to the alteration of the image. In this paper, a new fragile watermarking is proposed In which two watermarks are embedded in order to detect some modification occurred In high and low bit Planes. From simulation results, the embedded watermark is Invisible in a watermarked image and we can locale some Places where the modification occurring

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.28 no.9A
• /
• pp.710-716
• /
• 2003

OFDM is a very attractive technique for achieving high-bit-rate data transmission and high spectrum efficiency. However one of disadvantages of OFDM signal is the high PAPR characteristic when multicarriers are added up coherently. In this paper, we propose an adaptive PTS scheme using two threshold levels for PAPR reduction and reducing the amount of PAPR calculations with clipping scheme. Simulation results show that it is almost same between average bit error rate performance of the proposed scheme and that of a conventional scheme. Also, we obtain a great performance gain in the amount of calculations compared to the conventional scheme. Therefore, proposed system has a good performance in data processing time in OFDM wireless communication systems.