• 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.

• Proceedings of the IEEK Conference
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• 2000.06e
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• pp.85-88
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• 2000

This paper describes a Band-Selective Charge-Pump PLL(CPPLL) for clock recovery and clock generator. The proposed PLL satisfies fast acquisition time and low jitter characteristics simultaneously by reducing initial frequency error. The acquisition time of the designed Band-Selective CPPLL can be decreased down to 55% of a conventional CPPLL.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.10
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• pp.1968-1976
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• 2007

This paper proposes a hybrid pseudo-noise (PN) code acquisition scheme for Multicarrier Direct Sequence - Code Division Multiple Access (MC DS-CDMA) mobile communication systems on the code acquisition performance for Nakagami-m fading channel. The hybrid acquisition scheme combines parallel search with serial search to cover the whole uncertainty region of the input code phase. It has a much simpler acquisition hardware structure than the total parallel acquisition and can achieve the mean acquisition time (MAT) slightly inferior to that of the total parallel acquisition. The closed-form expressions of the detection and false-alarm probabilities are derived.

• International Journal of Advanced Culture Technology
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• v.7 no.2
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• pp.179-187
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• 2019

As the globalization process progresses more rapidly and widely, there has been a ever-growing demand for multilingual learning. Compared with the study of Second Language Acquisition, studies on the Third Language and even Multilingual Acquisition have attracted a relatively poor attention. At the same time, considering current educational environments for ethnic colleges and universities, the effects of college English teaching for minority students can be said to have been 'generally poor.' In this situation, when we try to find ways to improve college English studies for minority students most of whom already can speak two languages or even more, it would not be the best idea to keep following the experiences of traditional Second Language Acquisition. It is necessary first to find out whether there are positive or negative effects in acquiring multiple languages, and then to conduct a profound research on L3 (third language and even multilingual) Acquisition in order to employ more efficient teaching methods for multilingual learners. After conducting a Japanese-teaching experiment on two groups of learners with mono-lingual and bilingual backgrounds, it has been found that there is a positive transfer between different languages. In this paper, following the recent research findings on Language teaching for multilingual learners, I try to show with further supports that when it comes to language education for learners with multilingual backgrounds, we should focus on the advantages they may earn in order to conduct more effective language acquisition.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.6C
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• pp.649-655
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• 2009

Mean acquisition time (MAT) is the most important performance measure for code acquisition systems, where a shorter MAT implies a better code acquisition performance. Keshavarzian and Salehi proposed the multiple-shift (MS) algorithm for code acquisition in optical code division multiple access (O-CDMA) systems. Performing two steps acquisition, the MS algorithm has a shorter MAT than that of the conventional serial-search (SS) algorithm. In this paper, we propose a rapid code acquisition algorithm for O-CDMA systems. By using an efficient combination of local signals, correlation value, and the sign of correlation value, the proposed algorithm can provide a shorter MAT compared with that of the MS algorithm. The simulation results show that the proposed algorithm presents a shorter MAT than that of the MS algorithm.

• Investigative Magnetic Resonance Imaging
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• v.26 no.2
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• pp.125-134
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• 2022

Purpose: The aim of this study was to investigate the change in signal sensitivity over different acquisition start times and optimize the scanning window to provide the maximal signal sensitivity of [1-¹³C]pyruvate and its metabolic products, lactate and alanine, using spatially localized hyperpolarized 3D ¹³C magnetic resonance spectroscopic imaging (MRSI). Materials and Methods: We acquired 3D ¹³C MRSI data from the brain (n = 3), kidney (n = 3), and liver (n = 3) of rats using a 3T clinical scanner and a custom RF coil after the injection of hyperpolarized [1-¹³C]pyruvate. For each organ, we obtained three consecutive 3D ¹³C MRSI datasets with different acquisition start times per animal from a total of three animals. The mean signal-to-noise ratios (SNRs) of pyruvate, lactate, and alanine were calculated and compared between different acquisition start times. Based on the SNRs of lactate and alanine, we identified the optimal acquisition start timing for each organ. Results: For the brain, the acquisition start time of 18 s provided the highest mean SNR of lactate. At 18 s, however, the lactate signal predominantly originated from not the brain, but the blood vessels; therefore, the acquisition start time of 22 s was recommended for 3D ¹³C MRSI of the rat brain. For the kidney, all three metabolites demonstrated the highest mean SNR at the acquisition start time of 32 s. Similarly, the acquisition start time of 22 s provided the highest SNRs for all three metabolites in the liver. Conclusion: In this study, the acquisition start timing was optimized in an attempt to maximize metabolic signals in hyperpolarized 3D ¹³C MRSI examination with [1-¹³C] pyruvate as a substrate. We investigated the changes in metabolic signal sensitivity in the brain, kidney, and liver of rats to establish the optimal acquisition start time for each organ. We expect the results from this study to be of help in future studies.

• The Journal of Korea Robotics Society
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• v.13 no.3
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• pp.182-189
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• 2018

The purpose of this paper is to suggest the methodology for the establishment of operational concept for speed-up of defense robot and improvement direction of the defense acquisition system for the defense robot. In order to achieve this goal, the current defense acquisition system was analyzed into long-term planning, mid-term programming, and project execution stages. And I suggest the methodology for the establishment of operational concept for speed-up of defense robot and direction of development of the defense robot acquisition system considering the characteristics of the robot in terms of core technologies of robot, robot ecosystem and effectiveness-based-robot-design, respectively. Based on the methodology for establishment of the operational concept of defense robot and development direction of the defense acquisition system presented in this study, it will be possible to design efficiently the defense robot in the future.

• Journal of information and communication convergence engineering
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• v.9 no.3
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• pp.305-309
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• 2011

This paper proposes a new rotational frequency detector (RFD) for phase-locked loop (PLL) or clock and data recovery (CDR) applications for fast frequency acquisition. The proposed RFD uses the four states finite state machine (FSM) model to accelerate the frequency acquisition time. It is modeled and simulated with MATLAB Simulink. The functionalities of the proposed RFD are examined and the results are compared to those of a conventional RFD. The proposed RFD's frequency acquisition time is four times faster than that of a conventional one. The proposed RFD incorporated with a phase detector (PD) in PLL or CDR is expected to improve the frequency and phase acquisition performance later greatly.

• Journal of the Korean Society of Systems Engineering
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• v.12 no.2
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• pp.29-38
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• 2016

The threats around Korea Peninsula have been dramatically increased because North Korea is developing the Nuclear ballistic missile, Submarine launched ballistic missile(SLBM), and many kinds of weapons for sudden provocations. Therefore, ROK navy needs the cutting-edge warship combat systems in order to defeat the enemy threats effectively in the sea. The paper analyzes current warship combat system acquisition process and studies US navy and other advanced countries acquisition process and their contraction trends. After that, the paper proposes the optimal acquisition process of warship combat system for the ROK navy based on our current situation and other advanced countries acquisition trends. The paper will dedicate the next generation warship combat system acquisition process.

• Journal of the Korean Society of Systems Engineering
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• v.5 no.2
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• pp.35-42
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• 2009

A newly established provision to enforce the systems engineering was added in the regulation for arms acquisition management in January 2009, and a systems engineering guidelines for defence acquisition is being developed. In this paper we conduct a comparative study of the defence acquisition system in the United States and the Republic of Korea, and propose a improving plan about the domestic defence acquisition system.