• Journal of Institute of Control, Robotics and Systems
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• v.18 no.10
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• pp.977-987
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• 2012

One of the most significant errors in the pseudo-range measurement performance of GNSSes (Global Navigation Satellite Systems) is their multipath error for high-precision applications. Several schemes to mitigate this error have been studied. Most of them, however, have been focused on the GPS (Global Positioning System) L1 C/A (Coarse/Acquisition) signal that was designed in the 1970s and is still being used for civil navigation. Recently, several modernized signals that were especially conceived to more significantly mitigate multipath errors have been introduced, such as Time Multiplexed and Composite Binary Offset Carrier (TMBOC and CBOC, respectively) signals. Despite this advantage, however, a problem remains with the use of TMBOC and CBOC modulations: the ambiguity of BOC (Binary Offset Carrier)-modulated signal tracking. In this paper, a novel unambiguous multipath error mitigation scheme for these modernized signals is proposed. The proposed scheme has the same complexity as HRCs (High Resolution Correlators) but with low ambiguity. The simulation results showed that the proposed scheme outperformed or performed at par with the HRC in terms of their multipath error envelopes and running averages in the static and statistical channel models. The ranging error derived by the mean multipath error of the proposed scheme was below 1.8 meters in an urban area in the statistical channel model.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.5C
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• pp.437-443
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• 2012

In this paper, we propose a novel unambiguous correlation function for binary offset carrier (BOC) signal acquisition. Specifically, we first find out that the side-peaks arise due to the fact that the BOC autocorrelation is the sum of the irregularly shaped BOC sub-correlations, and then, propose an unambiguous correlation function with no side-peak by combining the sub-correlations. The proposed scheme is shown to remove the side-peaks completely for any type of BOC signal and to provide a better acquisition performance than the conventional correlation functions.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37A no.12
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• pp.1145-1151
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• 2012

In this paper, we propose an unambiguous binary offset carrier (BOC) correlation function with narrow main-peak width for BOC code tracking. Specifically, we first separate a subcarrier pulse into two rectangular pulses, obtain the associated partial correlations, and re-combine the partial correlations to yield the unambiguous correlation function with narrow main-peak width. From numerical results, it is demonstrated that the proposed correlation function provides a significant performance improvement over the conventional correlation functions.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.6
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• pp.521-530
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• 2016

Weather radar is observation equipment that transmits electromagnetic waves and receives backscattered signals from the targets. The weather radar systems of the Korea Meteorological Administration have a doppler mode that can extract the target's radial velocity. However, the radial velocity over the maximum unambiguous velocity(${\nu}_m$) for which is in a trade-off relationship with the maximum unambiguous range is folded. Therefore, a dual PRF mode of which transmits and receives signals using two different PRFs(high and low) must be used to extend the vm while maintaining the maximum unambiguous range. Using a dual PRF mode, vm can be extended to the amount of lowest common denominator of two observed vm from high and low PRF. For this extension, we have developed a velocity unfolding algorithm of which uses several criteria for classification considering observed velocity differences between high and low PRF and their error boundary. Then, correction factors are calculated for each class and are applied to unfold radial velocity. The developed algorithm was applied to the Yong-In Testbed(YIT) radar and the generated better performance of radial velocity extraction than those of the previous system.

• Korean Journal of Crystallography
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• v.16 no.2
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• pp.61-65
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• 2005

Despite a short history, the research on porous coordination polymers is gaining importance in inorganic chemistry thanks to facile synthesis, unambiguous characterization by X-ray diffraction and potentials as high-surface-area materials. Recently, gas sorption properties of various porous materials are under active investigations in order to know whether it is possible to store industrially important gases through physisorption, and porous coordination polymers are one of the most promising candidates for such a purpose. This article reviews two recent papers reporting a series of isomorphous frameworks based on Zn(II), dicarboxylate and diamine ligands and their gas sorption properties.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1451-1454
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• 2006

We propose a new electrical test method bringing repeatable and unambiguous test results eliminating drawbacks of the lighting test for LCD Cell manufacturing process. In this paper, we will show its basic concept, examples of actual test results and effectiveness of the method.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10a
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• pp.25-27
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• 2003

현재 웹이 가지고 있는 문제점들을 해결하기 위해서 연구하고 있는 차세대 웹을 시멘틱 웹이라고 한다. 시멘틱 웹에서 다루고 있는 기술들은 다양하지만 요즈음 가장 부각되고 있는 기술이 DAML-S이다. DAML-S는 DAML+OIL기술을 기반으로 확장된 레이어를 제공하여 웹 서비스의 모호성(unambiguous)을 제거하고, 상호 운용성을 증가시키는 역할을 하고 있다. 본 논문에서는 DAML-S로 정의된 웹 서비스를 FOL 추론방법을 이용해서 검색하는 시스템을 제안한다. 이를 위해서 DAML-S를 PSO TRIPLE 형태로 변환하는 전처리 방법과 FOL 질의 방법을 제안한다. 본 시스템을 이용하면 기존의 키워드 기반의 검색 방법에서는 불가능하였던 질의 작성이 가능해 지며, 추론을 이용한 정확한 서비스 검색이 가능해 진다.

• New Physics: Sae Mulli
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• v.68 no.12
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• pp.1378-1383
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• 2018

Multi-wavelength holography has a better axial range than single-wavelength holography, thus allowing unambiguous phase imaging. Noise amplification is the limiting factor in multi-wavelength holography as noise is amplified by a factor equivalent to the magnification of the wavelengths. Here, we propose a new algorithm to remove noise amplification in multi-wavelength holography. The proposed method does not use phase unwrapping and removes $2{\pi}$ ambiguities. Experiments and numerical simulations indicated that the proposed method is fast, has low noise, and is useful for measuring samples with arbitrary step heights.

• Proceedings of the Korean Magnestics Society Conference
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• 2008.12a
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• pp.10.1-10.1
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• 2008

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.11C
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• pp.694-701
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• 2011

This paper addresses a synchronization technique based on an adaptive combining of the sub-correlation functions obtained from multiband sine phased binary offset carrier (BOC) signals, allowing a BOC signal receiver to deal with multiband sine phased BOC signals. Specifically, we first obtain the sub-correlation functions composing the BOC autocorrelation function, and then, re-combine the sub-correlation functions generating a correlation function with no side-peak. Finally, by replacing the BOC autocorrelation with the correlation function with no side-peak in the delay lock loop, the proposed scheme performs unambiguous signal tracking. The proposed synchronization scheme is applicable to generic sine phased BOC signals. Numerical results demonstrate that the proposed scheme provides a performance improvement over the conventional unambiguous schemes in terms of the tracking error standard deviation.