• Journal of the Optical Society of Korea
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• 제15권2호
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• pp.182-186
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• 2011

A poling method using multiple negative voltage was introduced to fabricate periodically poled lithium niobate (PPLN) devices with quasi-phase matching (QPM) period of $12.9\;{\mu}m$ by utilizing an real-time visualization system. We also performed variation of the electric field during the poling. Two different conventionally used poling method, negative and positive single pulses, were used and the poling quality compared through microscopic images and far-field diffraction pattern analysis. Etched images on the +z and -z surfaces of PPLN showed that negative multiple pulse poling presented the highest periodicity in domain structures among the three methods. Duty ratio and its standard deviation were measured by analyzing far-field diffraction patterns. The newly introduced method of negative multiple pulse poling had duty ratio of 0.42 which was close to the ideal value of 0.50 and standard deviation of 0.020 that was about 3 times smaller than that of the other conventional methods.

• Journal of the Korea Institute of Military Science and Technology
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• 제11권6호
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• pp.135-141
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• 2008

In this paper, a design method of broadband horn antenna having 3:1 bandwidth and multiple polarization characteristics is proposed. The feeding section of the antenna adopts quadruple-ridged waveguide type for broadband and multiple polarization characteristics of the antenna. By inserting a shorting bar in the cavity structure with a semi-sphere type back short, the return loss at the feeding section was minimized. A corrugated dielectric lens is designed for phase compensation and lens-surface matching at the antenna aperture, which improves the antenna beam pattern. The validity of the design method is verified by indicating the measured data of the antenna.

• Journal of the Korea Computer Industry Society
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• 제2권12호
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• pp.1609-1616
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• 2001

We present an autostereoscopic 3D display system using volume hologram. In this proposed system, the interference pattern of angular multiplexed plane reference and object beams are recorded into a volume hologram, which plays a role of guiding object beams of multi-view images into the desired perspective directions. For reconstruction, object beams containing the desired multi-view image information, which satisfy Bragg matching condition, are illuminated in the time-division multiplexed manner onto the crystal. Then multiple stereoscopic images are projected to the display plane for autostereoscopic 3D viewing. It is possible to make a high resolution multiview 3D display system independent upon the viewpoint.

• Journal of the Korea Institute of Information and Communication Engineering
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• 제19권6호
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• pp.1462-1470
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• 2015

The container BIC-code is a transport protocol for convenience in international shipping and combined transport environment. It is an identification code of a marine transport container which displays a wide variety of information including country's code. Recently, transportation through aircrafts and ships continues to rise. Thus fast and accurate processes are required in the ports to manage transportation. Accordingly, in this paper, we propose a BIC-code region extraction and recognition method using multiple thresholds. In the code recognition, applying a fixed threshold is not reasonable due to a variety of illumination conditions caused by change of weather, lightening, camera position, color of the container and so on. Thus, the proposed method selects the best recognition result at the final stage after applying multiple thresholds to recognition. For each threshold, we performs binarization, labeling, BIC-code pattern decision (horizontal or vertical pattern) by morphological close operation, and character separation from the BIC-code. Then, each characters is recognized by template matching. Finally we measure recognition confidence scores for all the thresholds and choose the best one. Experimental results show that the proposed method yields accurate recognition for the container BIC-code with robustness to illumination change.

• Journal of the Korea Computer Industry Society
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• 제4권12호
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• pp.965-974
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• 2003

Today's network consists of a large number of routers and servers running a variety of applications. In this paper, we have designed and constructed the general simulation environment of network security model composed of multiple IDSs agent and a firewall agent which coordinate by CNP (Contract Net Protocol). The CNP, the methodology for efficient integration of computer systems on heterogeneous environment such as distributed systems, is essentially a collection of agents, which cooperate to resolve a problem. Command console in the CNP is a manager who controls the execution of agents or a contractee, who performs intrusion detection. In the knowledge-based network security model, each model of simulation environment is hierarchically designed by DEVS (Discrete Event system Specification) formalism. The purpose of this simulation is the application of rete pattern-matching algorithm speeding up the inference cycle phases of the intrusion detection expert system. we evaluate the characteristics and performance of CNP architecture with rete pattern-matching algorithm.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• 제11권5호
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• pp.81-86
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• 2011

In this paper, fractal microstrip patch antenna in a semicircle, by designing a multi-resonant antenna was improved by bandwidth issues, including the IEEE 802.11 wireless LAN and IEEE802.16e-band mobile WiMax specification both of which can contain non-directional antenna design and measured characteristics of the antenna for multi-resonant resonant frequency, impedance matching, radiation pattern, brilliantly polarity and multiple independent frequencies that can be controlled to meet the three semicircular wireless communications by inserting fractal patch antenna was designed.

• The Journal of Korean Institute of Communications and Information Sciences
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• 제25권5A호
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• pp.688-695
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• 2000

We present a multi-view autostereoscopic display system based on volume holographic storage technique. In this proposed system, the interference pattern of spatial multiplexed plane reference and angular multiplexed plane object beams are recorded into a photorefractive crystal, which plays a role of guiding object beams of multi-view images into the desired persfective directions. For reconstruction, object beams containing the desired multi-view image information, which satisfy Bragg matching condition, are illuminated in the time-division multiplexed manner onto the crystal. Then multiple stereoscopic images are Projected to the display plane for autostereoscopic 3D viewing.

• The Journal of Korean Institute of Communications and Information Sciences
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• 제21권4호
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• pp.972-983
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• 1996

This paper proposes a new technique for frequency offset correction for OFDM systems on a frequency selective fading channel. Frequency offset in OFDM introduces interchannel interference among the multiple subcarriers of OFDM signal. To compensate the interference, this paper describes an algorithm with two stages:acquisition and tracking. At both stages, the proposed algorithm oversamples the received OFDM signal to obtain a couple of demodulated symbol sets. At acquisition stage the frequency offset is reduced to half or less of the intercarrier spacings by matching the sign pattern of each element of the sets. Next, at tracking stage the frequency offset is corrected with a frequency detector which is controlled by the correlation of the two sets. It is shown that the proposed algorithm can correct the frequency offset in the event of uncertainty in the initial offset that exceeds one half of the intercarrier spacing. In addition, the proposed algorithm is robust to transmitted symbols and channel characteristics by using oversampled symbol sets.

• ETRI Journal
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• 제31권3호
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• pp.271-281
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• 2009

This paper presents a novel multiband microstrip-fed right angle slot antenna design technique for multiple independent frequency bands. The new technique uses various slot sizes at various appropriate positions. We first propose a tri-band slot antenna consisting of three right angle slots. Then, a quad-band slot antenna is developed with four right angle slots which achieves slant ${\pm}45^{\circ}$ linear polarization, omnidirectional pattern coverage, good antenna gain, and acceptable impedance bandwidths over all the operating frequency range. Moreover, an open-circuited tuning stub is introduced to achieve good impedance matching. Both proposed antennas are designed on a ground plane of RT/duroid 5880 substrate with a thickness of 1.575 mm. The real measurable results show that the desired frequencies used in wireless communication systems, namely, WLAN and WiMax, are efficiently achieved.

• Women's Health Nursing
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• 제23권3호
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• pp.155-165
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• 2017

Purpose: The aim of this study was to understand the hand-on breast massage techniques used by well-known experts in breastfeeding clinics. Methods: A qualitative multiple-case design was applied that involved a feasibility test. Four experts sampling qualitative data collected by observing participants and in individual interviews were analyzed by content analysis, linking data to the propositions, and cross-case pattern matching. This study explored differences within and between cases, and the possibilities of replicating findings across cases. Thirty-nine postpartum women participated voluntarily in the feasibility test, which investigated the usability of four massage techniques. Results: The four techniques showed considerable similarities in terms of the application of stimulation to the breast base and increased flexibility of the wired flexible body, which was the core mechanism underlying the techniques. The breast management strategies were consistent with existing practice guidelines with the exception of using cold cabbage to control engorgement pain. There was insufficient scientific evidence for supporting the massage techniques used by the experts. All of the techniques showed 100% education completeness, but application rates were higher for self-control-oriented techniques. Conclusion: The massage techniques applied by experts in breastfeeding were based on hypotheses and self-control techniques are feasible to apply in practice.