• The Journal of Korean Physical Therapy
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• v.23 no.1
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• pp.37-43
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• 2011

Purpose: We studied the changes in motor response time and stop signal response time following visuomotor skill learning of a stop signal task in young healthy subjects. This study also was designed to determine what an effective practice is for different stop signals in the stop signal task (SST). Methods: Forty-five right-handed normal volunteers without a history of neurological dysfunction were recruited. They all gave written informed consent. In all subjects, motor reaction time (RT) and stop signal reaction time (SSRT) were measured for the stop signal task. Tasks were classified into three categories: predictable-stop signal task (P-SST) practice group random-stop signal task (R-SST) practice group control group. Results: Motor reaction time in the P-SST was significantly reduced when comparing pre- and post-tests (p<0.05). Stop signal reaction times in the P-SST and the R-SST were significantly reduced following motor skill learning (p<0.05). Also, the reaction time of the R-SST was shorter than that of the P-SST. Conclusion: These findings indicate that practice of an SST improves motor performance and stop function for some stop signals in the SST. P-SST practice was effective in the stop function of regular movement because of faster of the motor prediction and preparation but the R-SST was effective in the stop function of movements because of faster motor selection.

• Phonetics and Speech Sciences
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• v.5 no.4
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• pp.137-143
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• 2013

Recent investigation of acoustic correlates of Korean stop manner contrasts has reported a diachronic transition in Korean stops: young Seoul speakers are relatively more dependent on the F0 characteristics of the stops than on the VOT characteristics in aspirated and lenis stop distinction. This finding has been examined against tonal dialects of Korean and the results suggested that the speakers of tonal dialects are not sharing the transition. These results also suggested that F0 function for segmental stop classification interferes with the function for lexical tone classification in their tonal speech. The current study investigated these findings in terms of perception. Perceptual behavior of Seoul and Busan speakers of Korean was examined in a comparative manner through the measurement of perceptual cue weight of F0 and VOT in particular. The results from regression and correlation analyses revealed that Busan speakers are closer to older Seoul speakers than to younger Seoul speakers in that the cue weight for VOT and F0 were comparable in the aspirated-lenis stop distinction. This result was in contrast to the perceptual behavior of younger Seoul speakers who showed clear dominance of F0 over VOT for the same distinction. These findings provided perceptual evidence of the dual function of F0 for segmental and lexical distinctions in tonal dialects of Korean.

• Phonetics and Speech Sciences
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• v.15 no.3
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• pp.45-52
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• 2023

Previous studies have established a role for cognitive differences in explaining variability in speech processing across individuals. In the case of perceptual cue weighting in the context of a sound change, studies have produced conflicting results regarding the relationship between executive function and the use of redundant cues. The current study aimed to explore this relationship in acoustic cue weighting during speech production. Forty-one Korean-speaking children read a list of stop-initial words and completed two tests that assess executive function, i.e., Dimensional Change Card Sorting (DCCS) and digit n-back. Voice onset time (VOT) and fundamental frequency (F0) were measured in each word, and analyses were carried out to determine the extent to which children's executive function predicted their use of both informative and less informative cues to the three pairs comprising the Korean three-way stop laryngeal contrast. No evidence was found for a relationship between cognitive ability and acoustic cue weighting in production, which is at odds with previous, albeit conflicting, results for speech perception. While this result may be due to the lack of task demands in the production task used here, it nevertheless expands the empirical ground upon which future work in this area may proceed.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.260-269
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• 2009

A station is the place for the passenger who load the baggage or for bus, taxi, train to stop regularly. For example, bus stop which is installed on many areas for bus as a public transportation provides some space to the passenger who waits for getting on the bus. The bus stop built up recently carries on many kinds of function to make the passenger convenient different from the conventional simple bus stop. Smart station for Bimodal Tram combined with ITS(Intelligent Transportation System) technology has the advantages of both new and conventional stations. This paper has investigated the function and role of newly developed smart station which is able to be adaptive to the rapid variation of road station.

• The Journal of Korean Physical Therapy
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• v.23 no.3
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• pp.65-70
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• 2011

Purpose: We investigated the changes in the stop-signal reaction time (SSRT) and the no-signal reaction time (NSRT) following motor sequential learning in the stop-signal task (SST). This study also determined which of the reduction0s of spatial processing time was better between blocked- and random-SST. Methods: Thirty right-handed healthy subjects without a history of neurological dysfunction were recruited. In all subjects, both the SSRT and the NSRT were measured for the SST. Tasks were classified into two categories based on the stop-signal patterns, the blocked-SST practice group and random-SST practice group. All subjects gave written informed consent. Results: In the blocked-SST group, both the SSRT and the NSRT was significantly decreased (p<0.05) but not significantly changed in the random-SST group. In the SSRT and the NSRT, the blocked-SST group was faster than the random-SST group (p<0.05). In the post-test SST after practice of each group, the SSRT was significantly decreased in the random-SST group (p<0.05), but the NSRT showed no significant changes in either group. Conclusion: These findings demonstrate that random-SST practice resulted in a decrease in internal processing times needed for a rapid stop to visual signals, indicating motor skill learning is acquired through improved response selection and inhibition.

• Phonetics and Speech Sciences
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• v.12 no.3
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• pp.15-23
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• 2020

This study examines the duration of Korean lax and tense stops in the prosodic word-medial position, their interactions with nearby segments, and the phonological implications of these interactions. It first examines the lengthening of consonants at the function of the short lax stop. Experiment 1 shows that the sonorant C1 is significantly longer before a short lax stop C2 than before a long tense stop. Experiment 2 shows that the short lax stop C1 cancels the contrast between the lax and tense obstruent at C2, making them appear as long tense obstruents (Post-Stop Tensing Rule). We suggest that such lengthening phenomena occur in Korean to robustly preserve the contrastive length difference between C and CC. Second, this study examines the vowel shortening, known as Closed-Syllable Vowel Shortening, before a long tense stop or before the consonant sequence. Experiment 3 suggests that it be interpreted as temporal adjustment to make the interval from the onset of a vowel to the onset of the following vowel of near-equal length. Conclusively, we suggest that Korean speech be planned and controlled with two specific intervals. One is the duration of contrastive consonant intervals between vowels, and the other is the duration from the onset of a vowel to the onset of the following vowel.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.5
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• pp.1208-1220
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• 1996

In this paper, the performance of a Carrier Sense Multiple Access/Collision avoidance (CSMA/CA) protocol using stop-and-Wait automatic Repeat reQuest, which is adapted as a draft standard in IEEE 802.11, is analyzed using a mathematical method based on a renewal theory, and simulation checks are performed, which confirm the goodness of our anlysis. In order to anlayze of CSMA/CA, we model that network is composed of finite populationand channel is slotted. And, we consider the CSMA/CA protocol as a hybrid protocol of 1-persistent CSMA and p-persistent CSMA protocol. As resuls of analysis, we have found that the throughput is degraded and packet delay is increased as the number of stations, Acknowledgement (ACK) length and Distributed coordination function Inter Frame Space (DIFS) length are increased.

• Phonetics and Speech Sciences
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• v.13 no.3
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• pp.21-29
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• 2021

The present study investigated how one's cognitive resources are related to speech perception by examining Korean speakers' executive function (EF) capacity and its association with voice onset time (VOT) and f0 sensitivity in identifying Korean stop laryngeal categories (/t'/ vs. /t/ vs. /t^h/). Previously, Kong et al. (under revision) reported that Korean listeners (N = 154) in Seoul and Changwon (Gyeongsang) showed differential group patterns in dialect-specific cue weightings across educational institutions (college, high school, and elementary school). We follow up this study by further relating their EF control (working memory, mental flexibility, and inhibition) to their speech perception patterns to examine whether better cognitive ability would control attention to multiple acoustic dimensions. Partial correlation analyses revealed that better EFs in Korean listeners were associated with greater sensitivity to available acoustic details and with greater suppression of irrelevant acoustic information across subgroups, although only a small set of EF components turned out to be relevant. Unlike Seoul participants, Gyeongsang listeners' f0 use was not correlated with any EF task scores, reflecting dialect-specific cue primacy using f0 as a secondary cue. The findings confirm the link between speech perception and general cognitive ability, providing experimental evidence from Korean listeners.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1664-1667
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• 2005

The main function of Ball-Stop part is to operate power shift for vehicle with more than 5 ton when a driver changes gear using suitable force. This paper presents the implementation of a DFSS(Design For Six Sigma) for robust design of Ball-Stop part of power shift. The factors influencing Ball-Stop part performance is derived to find control factor. Based on this factor, contact force between head and detent pin analysis is performed to get optimal factor is analyzed and compared with contact force test result to verify reliability of design. This makes clear the reason why the proposed one is necessary and the role of DFSS.

• Speech Sciences
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• v.4 no.2
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• pp.157-177
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• 1998

An electroglottography (EGG) was used to investigate the function of the vocal folds during their vibration. In this study, four Korean native speakers and 10 vocal polyp patients were selected. To investigate the dynamic change of EGG waveforms for the three-way distinction of Korean stops, a DSP-Sona graph model 5500, a Rino- Laryngeal stroboscope, a CSL model 4300B and a Laryngograph were used. An EGG Model 4338 was used to exam the vocal polyp of patients' voices during high, low, comfortable pitch production. The purpose of this study is to investigate the characteristics of Korean stop consonants in relation to pitch and to observe laryngeal movement during vocal fold vibration and speech production. The basic data accumulated during this research can be applied in clinical treatment. The results are as follows: on the Korean stop consonants, the aspirated stop is the highest in the GOT and PC1. On the angle of vowel contour, the angle of lenis is smaller than the angle of heavily aspirated and glottalized stops. The fundamental frequency is lowest at the lenis stop, In vocal polyp patients', the low pitch range is smaller than in normal speakers'. The pitch break and the vocal fry were observed. The jitter and OQ value are higher in vocal polyp patients than in those of normal speakers'.