• Journal of the Korean Institute of Telematics and Electronics
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• v.24 no.1
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• pp.1-9
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• 1987

In this paper, the acquisition performance of a receiver that utilizes a non-coherent digital correlator is analyzed. In order to analyze the acquisition performance, the probability density function of a receiver output random variable has been derived approximately. Using this function, the acquisition performance of the coarse acquisition code receiver in a global positioning system is analyzed.

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.1
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• pp.106-113
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• 2011

This paper describes Data Acquisition & Analysis System(DAS) for analysis of the multi-function radar. There are various information - beam probing data, clutter map data, plot data, target tracking data, RT tracking data, radar signal processing data, interface data - this device saves. The most important thing of data analysis is that a researcher gets a view of the whole data. The DAS intergrates with all of the data and provides overall information on the time matters occur. This is very useful advantage for approaching the matter easily. System algorithms of multi-function radar are improved by using this advantage. As a result of, range blank region have fallen about 72% and it is able to keep track in jammer environment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.7C
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• pp.459-466
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• 2011

This paper addresses the problem in the acquisition of binary offset carrier (BOC) signals employed in global navigation satellite systems, which is caused by the multiple side-peaks of the BOC autocorrelation function. We first observe that the side-peaks arise due to the fact that the BOC autocorrelation is made up of the sum of the sub-correlations shaped irregularly, and then, propose a novel acquisition scheme based on a recombination of the sub-correlations with cyclostationarity. The proposed scheme is demonstrated to remove the side-peaks completely for any type of BOC signal and to provide a performance improvement over the conventional schemes in terms of the mean acquisition time.

• Investigative Magnetic Resonance Imaging
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• v.21 no.1
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• pp.20-27
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• 2017

Purpose: To evaluate quantification results of single breath-hold (SBH) magnetic resonance (MR) cine imaging compared to results of conventional multiple breath-hold (MBH) technique for left ventricular (LV) function in patients with cardiac arrhythmia. Materials and Methods: MR images of patients with arrhythmia who underwent MBH and SBH cine imaging at the same time on a 1.5T MR scanner were retrospectively reviewed. Both SBH and MBH cine imaging were performed with balanced steady state free precession. SBH scans were acquired using temporal parallel acquisition technique (TPAT). Fifty patients ($65.4{\pm}12.3years$, 72% men) were included. End-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), ejection fraction (EF), myocardial mass, and LV regional wall motion were evaluated. Results: EF, myocardial mass, and regional wall motion were not significantly different between SBH and MBH acquisition techniques (all P-values > 0.05). EDV, ESV, and SV were significant difference between the two techniques. These parameters for SBH cine imaging with TPAT tended to lower than those in MBH. EF and myocardial mass of SBH cine imaging with TPAT showed good correlation with values of MBH cine imaging in Passing-Bablok regression charts and Bland-Altman plots. However, SBH imaging required significantly shorter acquisition time than MBH cine imaging ($15{\pm}7sec$ vs. $293{\pm}104sec$, P < 0.001). Conclusion: SBH cine imaging with TPAT permits shorter acquisition time with assessment results of global and regional LV function comparable to those with MBH cine imaging in patients with arrhythmia.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.9C
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• pp.955-963
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• 2005

In this paper, we consider the noncoherent code acquisition problem using sequential schemes. We show that the outputs of the noncoherent receiver approximately have a central chi-square distribution under the null hypothesis through simulations. Based on this observation, simplified acquisition schemes are obtained using the approximations of the Bessel function. The performance of the simplified and original schemes are compared in additive white Gaussian noise and slowly varying fading channels. Numerical results show that the simplified schemes have essentially the same performance as the original schemes.

• 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.

• ETRI Journal
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• v.20 no.1
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• pp.16-27
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• 1998

In this paper, we consider the acquisition performance of an IS-95 reverse link access channel slot as a function of system design parameters such as postdetection integration length and the number of access channel message block repetitons. The uncertainty region of the reverse link spreading codes compared to that of forward link is very small, since the uncertainty region of the reverse link is determined by a cell radius. Thus, the parallel acquisiton technique in the reverse link is more efficient than a serial acquisition technique in terms of implementation and of acquisition time. The parallel acquisition is achieved by a bank of N parallel I/Q noncoherent correlator are analyzed for band-limited noise and the Rayleigh fast fading channel. The detection probability is derived for multiple correct code-phase offsets and multipath fading. The probability of no message error is derived when rake combining, access channel message block combining, and Viterbi decoding are applied. Numerical results provide the acquisition performance for system design parameters such as postdetection integration length and number of access channel message block repetitions in case of a random access on a mobile station.

• Journal of the military operations research society of Korea
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• v.24 no.2
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• pp.170-186
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• 1998

The purposes of this paper are applying the IDEF(Integrated DEFinition), which was selected for standard methodology of CALS(Computer-aided Acquisition and Logistic Support) process modeling, to the acquisition process of the weapon system to activate DEfense CALS of the acquisition and management business of weapon system on Defense Planning and Management System and developing a AS-IS model which is usable and that the analysis of process problems results in. On this paper, We diagrammed the function of the acquisition and management of weapon system by using IDEF0 and presented AS-IS model. This paper focused on the development of AS-IS model which can put to practical use to find the problems of current acquisition and management process of weapon system and the embodiment of national defense CALS system. So more detailed analysis of current system and additional studies about TO-BE model would be the future research area.

• Journal of Information Science Theory and Practice
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• v.4 no.3
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• pp.28-42
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• 2016

Smartphones have become one of the most prevalent information devices in the current information environment. Although many people use smartphones for communication and information acquisition, these two functions are closely related and cannot be separated. However, many studies have focused on identifying each function of a smartphone independently. There are few studies that investigate the relationships between communication and information acquisition functions on smartphones. This research empirically analyzed and identified the relationships between these two functions of smartphones by conducting a survey. The results of the analysis showed that the activities for information acquisition make differences in communication on a smartphone. People who want to acquire more information tend to use a smartphone for communication purposes. Besides, communication activities on a smartphone also affect the acquisition of information. In addition, communication activities on a smartphone also affect the establishment of interpersonal relationships that lead to the acquisition of more information. From these results, it is identified that communication activities and information acquisition are interrelated when satisfying the information needs of smartphone users. Especially, communication activities on a smartphone positively affect people's information activities and enhance information acquisition.

• Smart Structures and Systems
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• v.29 no.1
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• pp.195-206
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• 2022

Crack detection is essential for inspection of existing structures and crack segmentation based on deep learning is a significant solution. However, datasets are usually one of the key issues. When building a new dataset for deep learning, laborious and time-consuming annotation of a large number of crack images is an obstacle. The aim of this study is to develop an approach that can automatically select a small portion of the most informative crack images from a large pool in order to annotate them, not to label all crack images. An active learning method with difficulty learning mechanism for crack segmentation tasks is proposed. Experiments are carried out on a crack image dataset of a steel box girder, which contains 500 images of 320×320 size for training, 100 for validation, and 190 for testing. In active learning experiments, the 500 images for training are acted as unlabeled image. The acquisition function in our method is compared with traditional acquisition functions, i.e., Query-By-Committee (QBC), Entropy, and Core-set. Further, comparisons are made on four common segmentation networks: U-Net, DeepLabV3, Feature Pyramid Network (FPN), and PSPNet. The results show that when training occurs with 200 (40%) of the most informative crack images that are selected by our method, the four segmentation networks can achieve 92%-95% of the obtained performance when training takes place with 500 (100%) crack images. The acquisition function in our method shows more accurate measurements of informativeness for unlabeled crack images compared to the four traditional acquisition functions at most active learning stages. Our method can select the most informative images for annotation from many unlabeled crack images automatically and accurately. Additionally, the dataset built after selecting 40% of all crack images can support crack segmentation networks that perform more than 92% when all the images are used.