• Journal of Korea Multimedia Society
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• v.25 no.8
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• pp.983-990
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• 2022

In this paper, we implemented a hierarchical encryption system using two-step phase-shifting digital holography(PSDH) technology based on XOR and scramble operations. The proposed encryption system is a system that authenticates access through the issuance of an encryption key for access to individual laboratories, department offices, and universities. In the encryption process, we proposed a double encryption method using XOR and scramble operation with digital technology and two-step phase-shifting digital holography with optical technology. In the two-step PSDH process, an new method of determining the reference wave intensity without measuring it by using random common object image gererated from digital encryption process was also proposed. In the decryption process, the process is performed in the reverse order of encryption process. And only when the various key information used in the encryption process is correct, the encrypted information can be decrypted, so that the user can access the desired place. That is, there is a feature that can hierarchically control the space that can be accessed according to the type of key issued in the proposed encryption system. Through the computer simulation, the feasibility of the proposed hierarchical encryption system was confirmed.

• Journal of Digital Convergence
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• v.14 no.12
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• pp.209-215
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• 2016

The quantity of image frames, the widths of transparent slits, and the black bars on the scanline are the three basic elements of scanimation. Besides, the size of scanimation, the color and contrast of scanimation, and the brightness of scanline, etc, can also influence the optical illusion of scanimation. Based on the recent principle of production of 2D scanimation, and through asking questions, and making corresponding experiment, this research finally gets to the conclusion. Based on the principle of production of 3D scanimation, and through various basic testing, this paper aims to verify how to bring out the best visual effects (optical illusion) of animated illusion scanimation in publications by using the 3D animation in the publications. And the future goal is to study and flexibly use Z-axis space in the scanimation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1514-1517
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• 2005

In recent years, as the demands of VBNS(Very high speed Backbone Network Service) and VDSL(Very high-data rate Digital Subscriber Line) increase, the development of kernel parts of optical communication such as PLC(Planar Light Circuit), Coupler, WDM elements increase. The alignment and the attachment technology are very important to fabricate the optical elements for communication. In this paper, the mechanism of rotational stage are studied. with the three different method and the results of them are applied to the design of the system. The performance test of resolution and travel is performed.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2005.05a
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• pp.150-155
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• 2005

In recent years, as the demands of VBNS(Very high speed Backbone Network Service) and VDSL(Very high-data rate Digital Subscriber Line) increase, the development of kernel parts of optical communication such as PLC(Planar Light Circuit), Coupler, WDM elements increase. The alignment and the attachment technology are very important to fabricate the optical elements for communication. In this paper, the mechanism of rotational stage are studied. with the three different method and the results of them are applied to the design of the system. The performance test of resolution and travel is performed.

• Journal of Sensor Science and Technology
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• v.15 no.4
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• pp.297-301
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• 2006

We have fabricated a multi-mode nonlinear plastic optical fiber (POF) using organic nonlinear optical materials and demonstrated the propagation of light. The refractive indices of core and cladding are 1.5240 and 1.5172. We made a POF preform by rod-in tube method. The core diameter of the fabricated POF is about $30{\mu}m$. We evaluated the temperature characteristics of POF. The sensitivity is $0.345{\;}mW/^{\circ}C$ and the linearity of sensor was good.

• Journal of Digital Convergence
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• v.10 no.4
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• pp.265-270
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• 2012

The subscriber access network is cause of the bottleneck phenomenon because equipment and infrastructure were not originally designed for busty high-bandwidth traffic between MAN(Metro Area Network) and LAN(Local Area Network). Whether riding on shorter copper drops or optical fiber, Ethernet is emerging as the future broadband protocol of choice, offering plug and play simplicity, and low cost. EPON(Ethernet Passive Optical Network) combines point-to-multipoint optical infrastructure with low-cost high-bandwidth Ethernet. The future broadband access network will be a combination of point-to-point and point-to-multipoint Ethernet, optimized for transporting IP data, as well as time critical voice and video. EPON is being considered as a novel communications infrastructure for next-generation broadband access network for the convergence of low-cost Ethernet equipment and low-cost fiber infrastructure. But, EPON has a problem with duplex multimedia services. It is the insufficiency of bandwidth for upstream. Because all ONUs use a shared transmission media for upstream. In this paper, we addressed the problem of upstream bandwidth in EPONs. We presented a wavelength division EPON supporting QoS in the differentiated services framework.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.11
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• pp.9-14
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• 1999

In this paper, a method of one line transmission of 622Mbps to interface a low speed part with a high speed part is introduced instead of H-BUS method of the 10 line transmission of 77.76Mbps in the 10Gbps optical transmission system. For this method, a reframing method to align the received data of 622Mbps transmission to STM(Synchronous Transfer Mode)-64 frame of SDH(Synchronous Digital Hierarchy) is described. Reframing is designed with VHDL and applied in the 10G-S4 ASIC of T14U board of 10Gbps optical transmission system.

• Journal of The Korean Astronomical Society
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• v.29 no.spc1
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• pp.389-390
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• 1996

The CCDs are widely used in astronomical observations either in direct imaging use or spectroscopic mode. However, the areas of available sensors are too small for large imaging format. One possibility to obtain large detection area is to assemble mosaics of CCD, and drive them simultaneously. Parallel driving of many CCDs together rules out the possibility of individual tuning; however, such optimisation is very important, when the ultimate low light level performance is required, particularly for new, or mixed devices. In this work, a new concept is explored for an entirely novel approach, where the drive waveforms are multiplexed and interleaved. This simultaneously reduces the number of leadout connections and permits individual optimisation efficiently. The digital controller can be designed within a single EPLD (Erasable Programmable Logic Device) chip produced by a CAD software package, where most of the digital controller circuits are integrated. This method can minimise the component. count., and improve the system efficiency greatly, based on earlier works by Han et a1. (1996, 1994). The system software has an open architecture to permit convenient modification by the user, to fit their specific purposes. Some variable system control parameters can be selected by a user with a wider range of choice. The digital controller design concept allows great flexibility of system parameters by the software, specifically for the compatibility to deal with any number of mixed CCDs, and in any format, within the practical limit.

• Journal of the Optical Society of Korea
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• v.18 no.5
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• pp.605-610
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• 2014

Clouds play an important role in climate change, in the prediction of local weather, and also in aviation safety when instrument assisted flying is unavailable. Presently, various ground-based instruments used for the measurements of the cloud base height or velocity. Lidar techniques are powerful and have many applications in climate studies, including the clouds' temperature measurement, the aerosol particle properties, etc. Otherwise, it is very circumscribed in cloud velocity measurements because there is no Doppler effect if the clouds move in the perpendicular direction to the laser beam path of Doppler lidar. In this paper, we present a method for the measurement of cloud velocity using lidar's range detection and DIC (Digital Image Correlation) system to overcome the disadvantage of Doppler lidar. The lidar system acquires the distance to the cloud, and the cloud images are tracked using the developed fast correlation algorithm of DIC. We acquired the velocities of clouds using the calculated distance and DIC algorithm. The measurement values had a linear distribution.

• Korean Journal of Optics and Photonics
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• v.14 no.2
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• pp.200-207
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• 2003

In this paper we present a new method of measuring the relative distance of two point objects in three-dimensional space by using phase-shifting digital holography. In our system the reference beam of a spherical wave is used instead of a plane wave. The system is computer simulated and built on an optical table for experiments. It is shown from computer simulations and experiments that the relative distance can be measured without the exact information on the reference beam used in the hologram record. It is shown from experiments that the relative distance between two point objects separated by 0.5 cm in the distance of about 300 cm from the CCD can be measured with an error less than 10％.