• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.05a
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• pp.718-721
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• 2011

In this paper, cross ambiguity function map is proposed to estimate the location of a unknown interferer which emits the harmful radio in the satellite communication network. To estimate the interferer, a time difference between received radio signals at earth stations and a frequency difference caused by the movement of interferers or receiving earth stations are calculated. Therefore, cross ambiguity function is used to calculate that values. The calculating process of the time and the frequency differences using cross ambiguity function is operated at every designated time then the correlation values between the time and frequency are calculated. After calcuation, the final location of the harmful interferer is estimated. From the simulation results, about 800 m distance error is occurred at 10~4 dB of $E_b/N_0$ and about 13 km distance errer is occurred at -20 dB of $E_b/N_0$.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.4
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• pp.184-193
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• 2015

Passive Surveillance System based on the TDOA detects the emitter position in the air using TOA of pulses comprising emitter signal from multiple receivers. In case that PRI of pulses from the emitter is not enough big in comparison with the distance among receivers, it causes the ambiguity problem in selecting proper pulse pairs for TDOA emitter geolocation. In this paper, a novel ambiguity resolution method of radar pulses is presented by using genetic algorithm after changing ambiguity problem into optimization problem between TDOA of received pulses from each receiver and emitter position. Simulation results are presented to show the performance of the proposed method.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2004.11a
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• pp.95-98
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• 2004

GPS double difference, carrier phase measurements are ambiguous by an unknown inter number of cycle. High precision, relative GPS positioning can be obtained from a short time span of data if the integer double difference ambiguities can be determined efficiently. In this study, we used a ambiguities resolution method indicated by Clyde Goad. And I compared with ambiguities using Lambda method. The difference of ambiguities between two method is below ${\pm}$1.

• Language and Information
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• v.19 no.2
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• pp.127-153
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• 2015

Negative expressions have their semantic function of classical negation as a pure reverser of truth-values. They also have various kin and foes of their pragmatic functions such as association of bad feelings (Russell 1948), emphasis/attenuation by negative polarity items, sarcasm, and metalinguistic negation (MN). This paper explores how MN and descriptive negation (DN) differ and whether the difference creates pragmatic ambiguity (Horn 1987) or reflects merely contextual variations of one logical negation (Carston 1996). To test the debate, this paper treats certain degree modifiers licensed exclusively by MN as in Mia-ka POTHONG/Yekan yeppu-n key an-i-a [external neg] (vs. modifier NPIs like cenhye 'at all', licensed only by DN) and contrasts them with bad utterances of the MN modifiers in [short form neg] sentences (not for MN) such as Mia-ka POTHONG an yeppu-e. The ERP results of the well-formed vs. ill-formed conditions evoked the N400 at Cz in written stimuli and the N400 near the center on both hemispheres in spoken stimuli. The results suggest that the anomalies are meaning-related and tend to support the pragmatic ambiguity.

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.4
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• pp.590-597
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• 2011

The IDRS provides detection, classification and bearing/range estimation by performing wavefront curvature analysis on an intercepted active transmission from target. Especially, a estimate of the target bearing/range that significantly affects the optimal operation of own submarine is required. Target bearing/range can be estimated by wavefront curvature ranging which use the difference of time arrival at sensors. But estimation ambiguity occur in bearing/range estimation due to a number of peaks caused by high center frequency and limited bandwidth of the intercepted active transmission and distortion caused by noise. As a result the bearing/range estimation performance is degraded. To estimate target bearing/range correctly, bearing/range estimation method that eliminate estimation ambiguity is required. In this paper, therefore, for wavefront curvature ranging, NLS cost function with curve fitting method is proposed, which provide robust bearing/range estimation performance by eliminating estimation ambiguity. Through simulation the performance of the proposed bearing/range estimation methods are verified.

• International Journal of Aeronautical and Space Sciences
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• v.5 no.2
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• pp.1-8
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• 2004

Real-Time Kinematic GPS positioning is widely used for many applications.Resolving ambiguities is the key to precise positioning. Integer ambiguity resolution isthe process of resolving the unknown cycle ambiguities of double difference carrierphase data as integers. Two important issues of resolving are efficiency andreliability. In the conventional search techniques, we generally used chi-squarerandom variables for decision variables. Mathematically, a chi-square random variableis the sum of mutually independent, squared zero-mean unit-variance normal(Gaussian) random variables. With this base knowledge, we can separate decisionvariables to several normal random variables. We showed it with related equationsand conceptual diagrams. With this separation, we can improve the computationalefficiency of the process without losing the needed performance. If we averageseparated normal random variables sequentially, averaged values are also normalrandom variables. So we can use them as decision variables, which prevent from asudden increase of some decision variable. With the method using averaged decisionvalues, we can get the solution more quicklv and more reliably.To verify the performance of our proposed algorithm, we conducted simulations.We used some visual diagrams that are useful for intuitional approach. We analyzedthe performance of the proposed algorithm and compared it to the conventionalmethods.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.11
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• pp.5208-5213
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• 2011

In this paper, we proposed a new direction finding(DF) technology using TDOA(time-difference of arrival) and PDOA(phase difference of arriving signal) method. The proposed technology has a good DF accuracy without DF ambiguity. TDOA or PDOA technology is used to the most of intelligence systems in 21 century. The principle of TDOA is to receive a signal with two parallel antennas, measure the time difference of arrival signal, and converse the time difference to the direction of incident signal. Those technology make a DF system small size but the DF accuracy is low into short antenna installation distance. The principle of PDOA is similar to TDOA except measuring the phase difference of arrival signal, These technology get a good DF accuracy in short antenna installation distance but have a DF ambiguity. The proposed DF method is simulated into DF system operation environment with noise, and has a good DF accuracy.

• Journal of Korean Academy of Nursing Administration
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• v.9 no.4
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• pp.615-624
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• 2003

Purpose: The purpose of this study was to find out the role conflict and ways of copying of nurses as underwriters worked at life insurance companies in Korea. Method: The subjects were 141 underwriters who were working at 4 major life insurance companies in Korea. For finding the role conflicts, Role conflict and Ambiguity scale developed by Rizzo, House & Lirtzman(1970) was used, For the ways of coping, Ways of coping scale developed by Lazarus et al. (1984) was used. The statistical method used were mean, percentage, t-test, ANOVA and Turkey test by SAS program. Result: The mean of role conflict was 2.76, and its subcategories were intersender conflict 2.95, sequential order interrole conflict 3.13, interarole conflict 2.69, organizational conflict 2.69, ambiguity from the outcome or responses to one's behavior 2.60, ambiguity from clarity of behavior requirements 2.61. The mean of ways of coping was 2.42 and its subcategories were problem focused 2.42, wishful thinking 2.26, detachment 2.09, seeking social support 2.49, focusing positive 2.72, tension reduction 2.08. There is statistically significant difference between single and married person i.e, single was high than married about role conflict. And also there is statistically significant difference among religion groups i.e., christian was high than none about ways of copying. Conclusion: The results of this study suggest that nurses as underwriters' role conflicts and ways of coping were different that of clinical nurses' and examining medical insurance nurses', Therefore it need more detail repeat studies.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.8
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• pp.16-23
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• 2010

In this paper, we propose an efficient estimation algorithm to find unknown location of an earth station for a geostationary satellite system. A cross ambiguity function (CAF), using time difference of arrival (TDOA) and frequency difference arrival (FDOA), is usually used to estimate the unknown location of an unauthorized earth station which may invoke interference to the existing satellite systems. However, a practical estimation of the location data requires tremendous computational time of CAF, and this prohibits direct utilization of CAF. For this reason, we propose a computationally efficient algorithm which utilizes characteristics of TDOA and FDOA within CAF. The proposed algorithm greatly enhances the computational efficiency without any performance degradation. In addition, we demonstrate the simulation results on the estimation performance by the resolution of the CAF estimation. The results provided in this paper will be utilized at the real system implementation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.3
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• pp.410-413
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• 2012

This study describes the performance comparison to solve angle ambiguity needed to angle of arrival estimation in 2D radiometer. There are three algorithms to solve its ambiguity such as phase-comparison monopulse method, digital beam-forming method and least square error of the phase difference in 2D radar interferometer. To estimate two direction angles, phase-comparison monopulse method is sequentially applied to azimuth and elevation direction. To analyze the performance of these methods, probability of solving angle ambiguity and execution time have been chosen as performance indexes. Through the Monte Carlo simulation, we have verified that phase-comparison monopulse method is most effective in real-time signal processing application.