• Composites Research
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• v.19 no.3
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• pp.1-6
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• 2006

As the structures of the high performance electronic equipments and devices recently become more complex, the electromagnetic interference (EMI) and compatibility (EMC) have been very essential for commercial and military purposes. Thus, sensitive electrical devices and densely packed systems need to be protected from electromagnetic wave. In this research, glass fabric/epoxy composites containing conductive multi-walled carbon nanotube (MWNT) and carbon fiber/epoxy composites as electrical shielding materials were fabricated and electrical properties of the composites were measured. The concerning frequency band is from 300 MHz to 1 GHz. The performances of composite shielding enclosures were predicted using electromagnetic wave 3-D simulation tool, CST Microwave Studio. The shielding enclosure made of carbon fiber/epoxy composites were fabricated and the shielding effectiveness (SE) was measured in the anechoic chamber.

• Journal of IKEEE
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• v.28 no.3
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• pp.271-278
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• 2024

An encryption and decryption method using phase mapping of a gray scale image based on a phase-shifting interferometry principle is proposed in which an encrypted image is formed into complex digital hologram function by symmetric security key in the proposed encryption system.. The gray scale image to be encrypted is converted to phase mapped function that is mixed with a randomly generated binary security encryption key and is used as an input. Decryption of phase information is performed by complex digital hologram and security encryption key, which reconstructs the original gray scale image by phase unmapping. The proposed method confirms that correlation coefficient of the decrypted image is 0.995 when quantization level of CCD is 8-bits(2⁸=256 levels).

• Korean Journal of Optics and Photonics
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• v.17 no.3
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• pp.248-255
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• 2006

Most optical security systems use a 4-f correlator, Mach-Zehnder interferometer, or a joint transform correlator(JTC). Of them, the JTC does not require an accurate optical alignment and has a good potential for real-time processing. In this paper, we propose an image encryption system using a position shift property of the JTC in the Fourier domain and a random phase image. Our encryption system uses two keys: one key is a random phase mask and the other key is a position shift factor. By using two keys, the proposed method can increase the security level of the encryption system. An encrypted image is produced by the Fourier transform for the multiplication image, which resulted from adding position shift functions to an original image, with a random phase mask. The random phase mask and position shift value are used as keys in decryption, simultaneously. For the decryption, both the encrypted image and the key image should be correctly located on the JTC. If the incorrect position shift value or the incorrect key image is used in decryption, the original information can not be obtained. To demonstrate the efficiency of the proposed system, computer simulation is performed. By analyzing the simulation results in the case of blocking of the encrypted image and affecting of the phase noise, we confirmed that the proposed method has a good tolerance to data loss. These results show that our system is very useful for the optical certification system.

• Korean Journal of Plant Resources
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• v.23 no.2
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• pp.197-205
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• 2010

This study was carried out to investigate the flora and vegetation in wetland of Mueuido. The forest vegetation was classified into 2 communities group (Utricularia bifida-Eriocaulon sikokianum and Alnus japonica) and 6 communities (Rhynchospora chinensis, Phragmites communis, Molinia japonica, Ischaemum crassipes, Quercus serrata and Pinus rigida-Miscanthus sinesis). Resources vascular plants were composed of 30 families, 53 genera, 50 species and 8 varieties, totaling 58 taxa. Among the investigated resources plants, Utricularia bifida and Utricularia racemosa were rare and endangered species. The special plants based on floral region by Ministry of Environment were 5 taxa; V rank species 2 taxa, II rank species 1 taxa and I rank species 2 taxa. A naturalized plants was 1 species of totaling 290 species appeared in South Korea. The Life-form were Hydatophytes (20.7%), Geophyte (19%), Microphanerophytes (19%), Hemicryptophytes (17.2%), Nanophanerophytes (17.2%), Chamaephytes (5.2%), Therophytes (1.7%). In marsh-type wetland of Mueuido, we predict that bog-type swamp, where various type of swamp plants are distributed, is starting to be formed based on the fact that Utricularia bifida and Utricularia racemosa, insectivorous plants, are dominant and sphagnum also is found. Along with the notion, there are reportedly found serious damages around wetland by human being and we have to prepare protection plans against it.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.10
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• pp.2223-2229
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• 2010

The integrity monitoring of anomalous GPS signal have been researched because of the degradation of GPS satellite performance. It is known that anomalous GPS signal can occur by failure of GPS satellite, sudden increase of ionosphere delay error, SA, wrong modeling for navigation parameters from control segment, and an electromagnetic wave interference, etc. In case of GPS anomaly by satellites can arise from carrier frequency, code and navigation message. In this paper, the scenarios with navigation message errors were made by using GPS simulator, and the influences of GPS navigation message error to receiver were analysed. The anomalies of preamble, bits related TOW count message, subframe ID in HOW, bits related satellite healthy, and the other navigation message errors were described and simulated. Also, the number of satellites, DOP and pseudorange are analyzed to know how the anomalous signal can affect on GPS receiver.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.12 no.1
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• pp.28-42
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• 2013

Personal Rapid Transit(PRT) is a new unmanned transportation system using electricity. The purpose of the PRT is relieving the congestion of city traffic and connecting between inner city and airport, high-speed railroad. PRT requires to develop devices for the guarantee of safety and reliability. PRT as the mean of rail transportation must be equipped with control system for front rail sensing. Ultra Wide Band(UWB) radar system is suitable for PRT's detection because it has the advantage of low power consumption, low interference and high resolution. In this paper, an improved adaptive Constant False Alarm Rate(CFAR) algorithm is proposed and studied in various noise environments. The proposed algorithm improves performance in various noise environments compared to the Mean Level CFAR algorithms and other adaptive CFAR algorithms.

• Journal of Korea Multimedia Society
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• v.13 no.5
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• pp.684-690
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• 2010

Digitalized Image Information is variously used like to substitute or help human's visual ability. Unmanned observation Camera is useful for the preventing disaster, risk factor and object observation but it is mostly to depend on awareness for human's vision. The purpose of this paper is to show that Unmanned Aerial Camera carries out object recognition and autonomous position tracking. when the informations about a specific object are given. For this purpose, we have to solve complicated problems like change according to object movement and variation of color and brightness information with refraction, interference and scattering of light and noise from environmental factors like weather. But, as the first step we limit the scope of this study with simplified environment in this paper. Our goal is the study and experience about object recognition and tracking via simplified environment with unmanned aerial camera. We obtained successful results of this study and experiment.

• Journal of Korea Society of Industrial Information Systems
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• v.13 no.3
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• pp.110-116
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• 2008

In this paper, we proposed an improvement technique of image encryption using binary phase computer generated hologram(BPCGH) and multi exclusive-OR(XOR) operations. For the encryption process, a BPCGH that reconstructs the original image is designed, using an iterative algorithm, and the resulting hologram is regarded as the image to be encrypted. The BPCGH is encrypted through the exclusive-OR operation with the random generated phase key image. Then the encrypted image is divided into several slide images using XOR operations. So, the performance of encryption for the image is improved. For the decryption process, we cascade the encrypted slide images and phase key image and interfere with reference wave. Then decrypted hologram image is transformed into phase information. Finally, the original image is recovered by an inverse Fourier transformation of the phase information. If the slide images are changed, we can get various decrypted BPCGH images. In the proposed security system, without a random generated key image, the original image can not be recovered. And we recover another hologram pattern according to the slide images, so it can be used in the differentiated authorization system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.5
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• pp.574-580
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• 2016

In this paper, we will introduce the system that can control multiple vehicles on the road through Single Board Computers and V2I (Vehicle-To-Infrastructure). Also, we will propose the group evasive maneuver decision algorithm, which plays a critical role in deciding whether the vehicles in the system have to conduct evasive maneuvers to avoid obstacles on the road. In order to test this system, we have utilized Wi-Fi and TCP/IP for establishing the communication between multiple vehicles and the relay server, and observed their driving states on the road with obstacles. During the experiments, we have discovered that our original decision algorithm possesses high failure rate when there is frequency interference in ISM (Industrial Scientific Medical) band. In order to reduce this failure rate, we have implemented the data transition detector. This paper will focus on how the use of data transition detector can affect the reliability of the system under the frequency interference of ISM band. If this technology is improved and applied in the field, we will effectively deal with such dangerous situations as multiple collision accidents through vehicle-to-vehicle communication or vehicle-to-infrastructure communication. Furthermore, this can be applied to the autonomous driving technologies. This can be used as the reference data for the development of the similar system.

• Journal of the HCI Society of Korea
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• v.4 no.2
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• pp.1-8
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• 2009

User-centered design aims to develop device naturally without the interference of user' s conscious and unconscious behavior. Accordingly, designers need to understand their user's requirements, observe user behavior and interaction in the real environment. However, existing observations suggested a vast range of analysis system and observation techniques which are often ambiguous to the designers. Therefore, this research is aimed to propose an observation system for collecting data from user's behavior. In order to do so, we define the components and behavior level within the context of driving.