• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.1
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• pp.39-45
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• 2011

The processes for manufacturing a product differ depending on the characteristics of the product, and the information used or generated by the processes also varies. To implement a flexible and configurable Manufacturing Execution System (MES), a Data Acquisition System (DAS) that takes into consideration the characteristics of the manufacturing system is required. In this study, we design an information acquisition system that can process the information on equipments of a shop floor in real-time and that is adaptive to the changes in the shop floor. The system has a data parser module for flexible processing of the equipment status, a data mapper module to link the equipment status with a manufacturing process, and an SOA-based data integration module to transmit the processed information to other information systems such as MES and ERP. From the results of pilot study, its maintenance is easy even if new equipment or new manufacturing processes are adopted or if the equipments are rearranged.

• The Journal of the Korea Contents Association
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• v.7 no.1
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• pp.147-154
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• 2007

In this paper, we propose a new parallel search algorithm to acquire synchronization for UWB(Ultra Wideband) systems that reduces computation of the correlation. The conventional synchronization acquisition algorithms check all the possible signal phases simultaneously using multiple correlators. However it reduces the acquisition time, it makes high power consumption owing to increasing of correlation. The proposed algorithm divides the preamble signal to input the correlator into an m-bit bunch. We check the result of the correlation at first stage of an m-bit bunch data and predict whether it has some synchronization acquisition information or not. Thus, it eliminates the unnecessary operation and save the number of correlation. We evaluate the proposed algorithm under the AWGN and the multi-Path channel model with MATLAB. The proposed parallel search scheme reduces number of the correlation 65% on the AWGN and 20% on the multi-path fading channel.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.8C
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• pp.742-753
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• 2005

In this paper, we propose a rapid and reliable signal acquisition scheme for UWB (Ultra Wide Band) systems in typical indoor wireless channels. The proposed scheme is a two-step search with different thresholds and search window applied to a single correlator, where each step utilizes the single-dwell search with the bit reversal. Simulation results in IEEE 802. I5 Task Group .3a UWB indoor wireless channel show that the proposed scheme for the LHWB signals can achieve significant reduction of the required mean acquisition time as compared to the conventional single-dwell bit reversal search and double-dwell bit reversal search with more complex structure employing two correlators for various threshold levels. In addition, it is also observed that the proposed scheme can achieve much faster and reliable signal acquisition in noisy environments.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.1
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• pp.54-65
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• 2000

We propose a parallel acquisition scheme using antenna arrays for initial acquisition of direct-sequence spread-spectrum (DS-SS) signals. The proposed parallel scheme can lower substantially the range of detectable signal-to-noise ratio (SNR) as compared to the conventional parallel scheme with a single antenna. The proposed scheme uses the sum of the independent decision samples from antenna arrays corresponding to an identical subsequence of the pseudonoise (PN) code as a decision variable. We derive the probabilities of detection, missing, and false alarm under an additive white Gaussian noise (AWGN) channel and a flat Rayleigh fading channel. Using these, we get the mean acquisition time of the proposed scheme. From numerical results, we see that the acquisition performance becomes improved continually as the number of antennas increases.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.38 no.4
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• pp.22-32
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• 2001

In this paper, we propose an average acquisition time and hardware design of high speed PN code synchronous acquisition system using DMF(Digital Matched Filter) with new switching method in DS-SS/CDMA(Direct Sequence Spread Spectrum Code Division Multiple Access). In reality, the PN code synchronous acquisition system using DMF has very complicated hardware, high cost and high power consumption. The PN code synchronous acquisition system using proposed switching method DMF can overcome those disadvantages. Therefore, we can make hardware simple and obtain low power and high density by reducing the area by 1/5 against the conventional approaches of using either the matched filters or the serial correlators. The proposed system architecture is also simple and easily controllable since there is no square-term circuit after execution of digital filtering.

• Phonetics and Speech Sciences
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• v.6 no.4
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• pp.27-36
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• 2014

This study provided longitudinal examination of the Chinese learners' acquisition of Korean vowels. Specifically, I examined the Chinese learners' Korean monophthongs /i, e, ɨ, ${\Lambda}$, a, u, o/ that were created at the time of 1 month and 12 months, tried to verify empirically how they learn by dealing with their mother tongue, and Korean vowels through dealing with pattern of the Perceptual Assimilation Model (henceforth PAM) of Best (Best, 1993; 1994; Best & Tyler, 2007) and the Speech Learning Model (henceforth SLM) of Flege (Flege, 1987; Bohn & Flege, 1992, Flege, 1995). As a result, most of the present results are shown to be similarly explained by the PAM and SLM, and the only discrepancy between these two models is found in the 'similar' category of sounds between the learners' native language and the target language. Specifically, the acquisition pattern of /u/ and /o/ in Korean is well accounted for the PAM, but not in the SLM. The SLM did not explain why the Chinese learners had difficulty in acquiring the Korean vowel /u/, because according to the SLM, the vowel /u/ in Chinese (the native language) is matched either to the vowel /u/ or /o/ in Korean (the target language). Namely, there is only a one-to-one matching relationship between the native language and the target language. In contrast, the Chinese learners' difficulty for the Korean vowel /u/ is well accounted for in the PAM in that the Chinese vowel /u/ is matched to the vowel pair /o, u/ in Korean, not the single vowel, /o/ or /u/.

• The Journal of the Korea Contents Association
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• v.13 no.11
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• pp.845-855
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• 2013

In today's knowledge-based industries, knowledge can be said to be a significant factor that has a decisive impact on corporate competitiveness. Recently, Korean construction companies have been going through a difficult period of time because of various negative domestic and foreign factors, such as economic decline and a continued sluggish domestic construction market, mainly due to the Korean government's real estate regulations and increasing competition from overseas companies with improved technologies. To help domestic construction companies navigate such an environment, this study empirically analyzes how the nature of corporate knowledge impacts the acquisition, transfer and deployment of knowledge within the organization of a company. Through such empirical analysis, we looked into how internal attributes of corporate knowledge affect the acquisition, transfer and application of such knowledge for domestic construction companies, with the application of the structural equation modeling (SEM). According to the results of this study, it is clear that the attributes of corporate knowledge have a significant impact on the acquisition, transfer and application of corporate knowledge, and therefore on the managerial performance of domestic companies.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.6A
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• pp.685-692
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• 2008

In this paper, we propose a timing recovery loop for Inmarsat mini-m system downlink receiver. Inmarsat mini-m system requires a timing recovery loop which is robust in frequency offset and has fast acquisition because Inmarsat mini-m system specification requires frequency tolerance is required of ${\pm}924$ Hz (signal bandwidth: 2.4 kHz) and acquisition time of UW (Unique Word) signal duration (15ms).Therefore, we propose a timing recovery loop which is suitable for Inmarsat mini-m system. The proposed timing recovery loop adopted noncoherent UW detector and differential ELD which applied differential UW signal for stability and fast acquisition in frequency offset environment. Simulation results show that the proposed timing recovery loop has stable operation and fast acquisition in frequency offset environment for the system.

• Speech Sciences
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• v.11 no.2
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• pp.71-87
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• 2004

Korean has a pair of voiceless fricatives, whose laryngeal manifestation comes in parallel to stops and affricates with a three-way lexical contrast. Prior phonetic studies by Kagaya (1974), Iverson (1983), and Kang (1999, 2000) point out /s/ is associated with multiple characteristics of the larynx shared with not only the lax but also the aspirated series, whereas /s' / carries a laryngeal distinction typical of the tense consonants. The complex dual nature of /s/ is again supported by a psycholinguistic study by Kang (2004), as /s/ was found to interact with /$c^h$/ (17% of the time) as well as /c/ (57%) in speech errors. In addition, a recent work by Cho and Lee (2003) notes an interesting chain shift case in the acquisition of the fricatives. Although they observed a significant phonological pattern between child English and Korean, Cho and Lee's description of acquiring fricatives is far from being precise from the perspective of phonetics. From a longitudinal study of recorded tapes by two children at 1;7-3;8 and 1;7-2;1 respectively, I found that /s' / was usually substituted into tense noncontinuants in young children's early production as predicted, whereas /s/ having both lax and aspirated-like glottal properties revealed a complicated pattern of substitutions into lax, tense, and aspirated noncontinuants with a varying degree of preference relative to the subjects. The current acquisition study supports the previous claims concerning fricatives in other languages, showing that their acquisition comes after stops. Besides, it also notes that Korean fricatives are subject to a series of phonological processes called stopping, affricating, tensifying and palatalizing during the transitional period of phonological development by young children. Moreover, between the two voiceless types, /s/ was acquired earlier than /s'/ as the unmarked segment.

• 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.